Data Series
| Period | Period Average | End of Period |
| May-2021 | 413.17 | 413.96 |
| Apr-2021 | 415.92 | 414.03 |
| Mar-2021 | 412.73 | 414.03 |
| Feb-2021 | 414 | 413.94 |
| Jan-2021 | 413.69 | 414.03 |
| Dec-2020 | 413.29 | 414.03 |
| Nov-2020 | 413.99 | 413.94 |
| Oct-2020 | 414.01 | 414.03 |
| Sep-2020 | 414 | 413.94 |
| Aug-2020 | 414 | 413.94 |
| Jul-2020 | 413.95 | 413.97 |
| Jun-2020 | 414.01 | 413.92 |
| May-2020 | 413.47 | 411.03 |
| Apr-2020 | 413.64 | 414.03 |
| Mar-2020 | 413.65 | 414.03 |
| Feb-2020 | 414.02 | 414 |
| Jan-2020 | 413.89 | 411.58 |
| Dec-2019 | 414.01 | 414.03 |
| Nov-2019 | 413.88 | 414.03 |
| Oct-2019 | 414.02 | 414.03 |
| Sep-2019 | 414 | 414.03 |
| Aug-2019 | 413.9 | 414.03 |
| Jul-2019 | 414.03 | 414.03 |
| Jun-2019 | 414.01 | 414.03 |
| May-2019 | 414.01 | 414.06 |
| Apr-2019 | 414.02 | 414.06 |
| Mar-2019 | 414.03 | 414.06 |
| Feb-2019 | 414.01 | 414 |
| Jan-2019 | 414 | 414.03 |
| Dec-2018 | 414.03 | 414.03 |
| Nov-2018 | 414.01 | 414 |
| Oct-2018 | 414.01 | 414.03 |
| Sep-2018 | 414.01 | 414.03 |
| Aug-2018 | 414 | 414.03 |
| Jul-2018 | 413.97 | 414.03 |
| Jun-2018 | 414.01 | 414.03 |
| May-2018 | 414.01 | 414.03 |
| Apr-2018 | 414.01 | 414.03 |
| Mar-2018 | 414.02 | 414.03 |
| Feb-2018 | 414.02 | 414.03 |
| Jan-2018 | 414.02 | 414.03 |
| Dec-2017 | 414.02 | 414.03 |
| Nov-2017 | 412.85 | 414.06 |
| Oct-2017 | 411.91 | 413.92 |
| Sep-2017 | 413.94 | 414.06 |
| Aug-2017 | 414.03 | 414 |
| Jul-2017 | 413.42 | 413.89 |
| Jun-2017 | 410.99 | 401.46 |
| May-2017 | 413.99 | 414.01 |
| Apr-2017 | 414.02 | 413.98 |
| Mar-2017 | 414 | 414 |
| Feb-2017 | 414 | 413.98 |
| Jan-2017 | 414.01 | 414.02 |
| Dec-2016 | 413.98 | 413.99 |
| Nov-2016 | 414.01 | 414.01 |
| Oct-2016 | 413.99 | 413.98 |
| Sep-2016 | 414 | 413.96 |
| Aug-2016 | 414.02 | 413.99 |
| Jul-2016 | 413.98 | 413.97 |
| Jun-2016 | 414.08 | 413.99 |
| May-2016 | 414.08 | 414.1 |
| Apr-2016 | 413.99 | 414.1 |
| Mar-2016 | 413.99 | 414.02 |
| Feb-2016 | 413.99 | 414.03 |
| Jan-2016 | 413.98 | 414.09 |
| Dec-2015 | 413.98 | 413.89 |
| Nov-2015 | 414.03 | 413.9 |
| Oct-2015 | 414.02 | 414.11 |
| Sep-2015 | 413.98 | 413.89 |
| Aug-2015 | 413.96 | 413.97 |
| Jul-2015 | 413.99 | 414 |
| Jun-2015 | 414.06 | 414 |
| May-2015 | 414.14 | 414.16 |
| Apr-2015 | 414.09 | 414.11 |
| Mar-2015 | 413.99 | 414 |
| Feb-2015 | 413.98 | 414.01 |
| Jan-2015 | 414.01 | 413.97 |
| Dec-2014 | 413.97 | 413.93 |
| Nov-2014 | 413.99 | 414.07 |
| Oct-2014 | 413.97 | 413.99 |
| Sep-2014 | 413.99 | 413.96 |
| Aug-2014 | 413.99 | 414.01 |
| Jul-2014 | 414.08 | 414.03 |
| Jun-2014 | 414.06 | 414.02 |
| May-2014 | 414.07 | 414.15 |
| Apr-2014 | 414.03 | 414.05 |
| Mar-2014 | 413.98 | 414 |
| Feb-2014 | 413.97 | 413.97 |
| Jan-2014 | 413.99 | 413.98 |
| Dec-2013 | 414.01 | 413.98 |
| Nov-2013 | 414.05 | 414.05 |
| Oct-2013 | 414.01 | 414.15 |
| Sep-2013 | 414.06 | 414.01 |
| Aug-2013 | 413.97 | 413.98 |
| Jul-2013 | 413.99 | 413.99 |
| Jun-2013 | 414 | 414 |
| May-2013 | 414.04 | 414 |
| Apr-2013 | 414.06 | 414.13 |
| Mar-2013 | 414.08 | 414.03 |
| Feb-2013 | 414.06 | 414.07 |
| Jan-2013 | 414.09 | 414.11 |
| Dec-2012 | 414.05 | 414.05 |
| Nov-2012 | 414.03 | 414.06 |
| Oct-2012 | 414.05 | 414.02 |
| Sep-2012 | 414.02 | 414.02 |
| Aug-2012 | 414.03 | 414.02 |
| Jul-2012 | 414.04 | 414.03 |
| Jun-2012 | 414.03 | 414.01 |
| May-2012 | 414.04 | 414.06 |
| Apr-2012 | 414.03 | 414.06 |
| Mar-2012 | 414.04 | 414.05 |
| Feb-2012 | 414.02 | 414.09 |
| Jan-2012 | 414.02 | 413.98 |
| Dec-2011 | 414.03 | 413.99 |
| Nov-2011 | 413.99 | 413.97 |
| Oct-2011 | 414 | 413.99 |
| Sep-2011 | 413.99 | 413.98 |
| Aug-2011 | 414 | 414 |
| Jul-2011 | 413.99 | 414 |
| Jun-2011 | 413.99 | 413.99 |
| May-2011 | 413.99 | 413.97 |
| Apr-2011 | 413.99 | 413.94 |
| Mar-2011 | 413.98 | 414 |
| Feb-2011 | 413.96 | 413.97 |
| Jan-2011 | 414.03 | 414.01 |
| Dec-2010 | 414.01 | 414.17 |
| Nov-2010 | 414.04 | 413.99 |
| Oct-2010 | 414.09 | 414.11 |
| Sep-2010 | 414.1 | 414.13 |
| Aug-2010 | 414.16 | 414.13 |
| Jul-2010 | 414.13 | 414.19 |
| Jun-2010 | 414.01 | 414 |
| May-2010 | 414.06 | 414.02 |
| Apr-2010 | 414.09 | 414.09 |
| Mar-2010 | 414.2 | 414.06 |
| Feb-2010 | 413.98 | 414.14 |
| Jan-2010 | 414.02 | 414.06 |
| Dec-2009 | 413.98 | 413.92 |
| Nov-2009 | 414.08 | 414 |
| Oct-2009 | 414.03 | 414 |
| Sep-2009 | 413.99 | 413.99 |
| Aug-2009 | 414 | 413.94 |
| Jul-2009 | 414 | 413.98 |
| Jun-2009 | 414.16 | 413.94 |
| May-2009 | 414.12 | 414.13 |
| Apr-2009 | 414.09 | 414.14 |
| Mar-2009 | 414.02 | 414.05 |
| Feb-2009 | 413.98 | 414.02 |
| Jan-2009 | 414.03 | 413.91 |
| Dec-2008 | 413.93 | 413.91 |
| Nov-2008 | 413.99 | 413.97 |
| Oct-2008 | 413.94 | 413.97 |
| Sep-2008 | 414.03 | 413.97 |
| Aug-2008 | 414.08 | 414.08 |
| Jul-2008 | 414.04 | 414.09 |
| Jun-2008 | 414.07 | 414.08 |
| May-2008 | 414.09 | 414.01 |
| Apr-2008 | 414.27 | 414.15 |
| Mar-2008 | 414.44 | 414.31 |
| Feb-2008 | 414.38 | 414.26 |
| Jan-2008 | 414.1 | 414.32 |
| Dec-2007 | 414.2 | 414.09 |
| Nov-2007 | 414.52 | 414.72 |
| Oct-2007 | 414.33 | 414.43 |
| Sep-2007 | 414.21 | 414.25 |
| Aug-2007 | 414.14 | 414.1 |
| Jul-2007 | 414.16 | 414.21 |
| Jun-2007 | 414.18 | 414.16 |
| May-2007 | 414.15 | 414.16 |
| Apr-2007 | 414.18 | 414.13 |
| Mar-2007 | 414.18 | 414.19 |
| Feb-2007 | 414.13 | 414.17 |
| Jan-2007 | 414.06 | 414.05 |
| Dec-2006 | 414.07 | 414.09 |
| Nov-2006 | 414.06 | 414.06 |
| Oct-2006 | 414.09 | 414.06 |
| Sep-2006 | 414.1 | 414.11 |
| Aug-2006 | 414.09 | 414.05 |
| Jul-2006 | 414.1 | 414.08 |
| Jun-2006 | 414.1 | 414.08 |
| May-2006 | 414.11 | 414.03 |
| Apr-2006 | 414.11 | 414.13 |
| Mar-2006 | 414.16 | 414.06 |
| Feb-2006 | 414.22 | 414.21 |
| Jan-2006 | 414.13 | 414.32 |
| Dec-2005 | 414.08 | 414.09 |
| Nov-2005 | 414.07 | 414.03 |
| Oct-2005 | 414.07 | 414.03 |
| Sep-2005 | 414.15 | 414.08 |
| Aug-2005 | 414.16 | 414.09 |
| Jul-2005 | 414.23 | 414.31 |
| Jun-2005 | 414.24 | 414.11 |
| May-2005 | 414.23 | 414.32 |
| Apr-2005 | 414.22 | 414.31 |
| Mar-2005 | 414.28 | 414.31 |
| Feb-2005 | 414.25 | 414.32 |
| Jan-2005 | 414.2 | 414.21 |
| Dec-2004 | 414.16 | 414.13 |
| Nov-2004 | 414.17 | 414.19 |
| Oct-2004 | 414.14 | 414.14 |
| Sep-2004 | 414.1 | 414.14 |
| Aug-2004 | 414.08 | 414.09 |
| Jul-2004 | 414.15 | 414.09 |
| Jun-2004 | 414.08 | 414.16 |
| May-2004 | 414.07 | 414.06 |
| Apr-2004 | 414.07 | 414.07 |
| Mar-2004 | 414.06 | 414.02 |
| Feb-2004 | 414.03 | 414 |
| Jan-2004 | 414.04 | 414.03 |
| Dec-2003 | 414.11 | 414.15 |
| Nov-2003 | 414.12 | 414.17 |
| Oct-2003 | 414.09 | 414.25 |
| Sep-2003 | 414.05 | 414.06 |
| Aug-2003 | 414.08 | 414.09 |
| Jul-2003 | 414.18 | 414.26 |
| Jun-2003 | 414.25 | 414.26 |
| May-2003 | 414.19 | 414.21 |
| Apr-2003 | 414.08 | 414.14 |
| Mar-2003 | 414.11 | 414.13 |
| Feb-2003 | 414.05 | 414.05 |
| Jan-2003 | 414.04 | 414.07 |
| Dec-2002 | 414.05 | 414.08 |
| Nov-2002 | 414.04 | 413.99 |
| Oct-2002 | 414.06 | 414.07 |
| Sep-2002 | 414.06 | 414.07 |
| Aug-2002 | 414.09 | 414.09 |
| Jul-2002 | 414.08 | 414.05 |
| Jun-2002 | 414.08 | 414.11 |
| May-2002 | 414.08 | 414.07 |
| Apr-2002 | 414.03 | 414.02 |
| Mar-2002 | 414.04 | 414.06 |
| Feb-2002 | 414.03 | 414.03 |
| Jan-2002 | 414.09 | 414.03 |
| Dec-2001 | 414.13 | 414.21 |
| Nov-2001 | 414.05 | 414.06 |
| Oct-2001 | 414.07 | 414.06 |
| Sep-2001 | 414.06 | 414.06 |
| Aug-2001 | 414.06 | 414.06 |
| Jul-2001 | 414.11 | 414.07 |
| Jun-2001 | 414.12 | 414.07 |
| May-2001 | 414.1 | 414.18 |
| Apr-2001 | 414.08 | 414.11 |
| Mar-2001 | 414.06 | 414.21 |
| Feb-2001 | 414.08 | 414.15 |
| Jan-2001 | 414.07 | 414.06 |
| Dec-2000 | 414.1 | 414.23 |
| Nov-2000 | 414.08 | 414.14 |
| Oct-2000 | 414.08 | 414.06 |
| Sep-2000 | 414.07 | 414.06 |
| Aug-2000 | 414.12 | 414.14 |
| Jul-2000 | 414.1 | 414.21 |
| Jun-2000 | 414.09 | 414.09 |
| May-2000 | 414.07 | 414.07 |
| Apr-2000 | 414.09 | 414.17 |
| Mar-2000 | 414.13 | 414.09 |
| Feb-2000 | 414.08 | 414.09 |
| Jan-2000 | 414.09 | 414.06 |
| Dec-1999 | 414.14 | 414.06 |
| Nov-1999 | 414.07 | 414.09 |
| Oct-1999 | 414.08 | 414.09 |
| Sep-1999 | 414.11 | 414.03 |
| Aug-1999 | 414.18 | 414.14 |
| Jul-1999 | 414.2 | 414.19 |
| Jun-1999 | 414.2 | 414.29 |
| May-1999 | 414.18 | 414.14 |
| Apr-1999 | 414.11 | 413.12 |
| Mar-1999 | 414.21 | 414.17 |
| Feb-1999 | 414.09 | 414.17 |
| Jan-1999 | 414.24 | 414.21 |
| Dec-1998 | 414.35 | 414.23 |
| Nov-1998 | 414.37 | 414.5 |
| Oct-1998 | 414.44 | 414.37 |
| Sep-1998 | 414.97 | 414.71 |
| Aug-1998 | 415.59 | 415.3 |
| Jul-1998 | 416.18 | 415.85 |
| Jun-1998 | 416.8 | 416.52 |
| May-1998 | 417.34 | 417.11 |
| Apr-1998 | 417.7 | 417.54 |
| Mar-1998 | 417.97 | 417.8 |
| Feb-1998 | 418.68 | 418.41 |
| Jan-1998 | 419.13 | 418.96 |
| Dec-1997 | 419.64 | 419.41 |
| Nov-1997 | 420.27 | 420.03 |
| Oct-1997 | 420.83 | 420.49 |
| Sep-1997 | 421.4 | 421.16 |
| Aug-1997 | 422.05 | 421.78 |
| Jul-1997 | 422.61 | 422.33 |
| Jun-1997 | 423.22 | 422.97 |
| May-1997 | 423.75 | 423.51 |
| Apr-1997 | 424.27 | 423.99 |
| Mar-1997 | 424.9 | 424.61 |
| Feb-1997 | 425.4 | 425.16 |
| Jan-1997 | 426 | 425.7 |
| Dec-1996 | 426.55 | 426.34 |
| Nov-1996 | 427.12 | 426.83 |
| Oct-1996 | 427.79 | 427.44 |
| Sep-1996 | 428.45 | 428.07 |
| Aug-1996 | 429.62 | 429 |
| Jul-1996 | 430.89 | 430.32 |
| Jun-1996 | 432.06 | 431.53 |
| May-1996 | 433.21 | 432.57 |
| Apr-1996 | 434.46 | 433.98 |
| Mar-1996 | 435.46 | 434.91 |
| Feb-1996 | 436.62 | 436.14 |
| Jan-1996 | 437.66 | 437.19 |
| Dec-1995 | 438.83 | 438.35 |
| Nov-1995 | 439.85 | 439.31 |
| Oct-1995 | 441.56 | 440.7 |
| Sep-1995 | 442.84 | 442.32 |
| Aug-1995 | 443.62 | 443.14 |
| Jul-1995 | 444.67 | 443.98 |
| Jun-1995 | 445.68 | 445.07 |
| May-1995 | 447.06 | 446.18 |
| Apr-1995 | 448.6 | 448.2 |
| Mar-1995 | 449.65 | 449.12 |
| Feb-1995 | 450.78 | 450.32 |
| Jan-1995 | 451.89 | 451.44 |
| Dec-1994 | 453.07 | 452.45 |
| Nov-1994 | 455.65 | 454.92 |
| Oct-1994 | 456.93 | 456.32 |
| Sep-1994 | 458.33 | 457.69 |
| Aug-1994 | 459.79 | 459.07 |
| Jul-1994 | 461.07 | 460.58 |
| Jun-1994 | 462.07 | 461.67 |
| May-1994 | 463.38 | 462.64 |
| Apr-1994 | 464.96 | 464.38 |
| Mar-1994 | 466.31 | 465.65 |
| Feb-1994 | 467.95 | 467.3 |
| Jan-1994 | 469.28 | 468.71 |
| Dec-1993 | 470.58 | 469.99 |
| Nov-1993 | 471.81 | 471.25 |
| Oct-1993 | 472.89 | 472.25 |
| Sep-1993 | 475.07 | 474.74 |
| Aug-1993 | 475.02 | 475.42 |
| Jul-1993 | 476.58 | 476.53 |
| Jun-1993 | 475.94 | 475.65 |
| May-1993 | 476.57 | 476.03 |
| Apr-1993 | 479.25 | 478.23 |
| Mar-1993 | 481.73 | 479.97 |
| Feb-1993 | 488.9 | 479.97 |
| Jan-1993 | 503.16 | 502.75 |
| Dec-1992 | 508.53 | 505.06 |
| Nov-1992 | 525.32 | 514.95 |
| Oct-1992 | 617.74 | 539.95 |
| Sep-1992 | 695.37 | 664.98 |
| Aug-1992 | 654.61 | 656.74 |
| Jul-1992 | 509.93 | 594.91 |
| Jun-1992 | 475.52 | 468.51 |
| May-1992 | 445.46 | 461.64 |
| Apr-1992 | 396.44 | 439.66 |
| Mar-1992 | 322.75 | 351.57 |
| Feb-1992 | 255.31 | 294 |
| Jan-1992 | 241.54 | 241.54 |
| Dec-1991 | 241.48 | 241.54 |
| Nov-1991 | 242.1 | 241.57 |
| Oct-1991 | 243.59 | 242.72 |
| Sep-1991 | 245.13 | 244.92 |
| Aug-1991 | 245.27 | 245.28 |
| Jul-1991 | 246.46 | 245.28 |
| Jun-1991 | 249.71 | 248.43 |
| May-1991 | 253.19 | 251.32 |
| Apr-1991 | 258.77 | 255.99 |
| Mar-1991 | 269.29 | 257.64 |
| Feb-1991 | 297.06 | 291.15 |
| Jan-1991 | 267.59 | 304.89 |
| Dec-1990 | 217.27 | 231.27 |
| Nov-1990 | 194.09 | 192.27 |
| Oct-1990 | 239.6 | 188.15 |
| Sep-1990 | 297.44 | 256.24 |
| Aug-1990 | 211.99 | 274.04 |
| Jul-1990 | 181.82 | 183.61 |
| Jun-1990 | 182.38 | 182.38 |
| May-1990 | 174.49 | 172.9 |
| Apr-1990 | 160.83 | 166.16 |
| Mar-1990 | 153.53 | 156.83 |
| Feb-1990 | 151.69 | 152.78 |
| Jan-1990 | 149.58 | 150.38 |
| Dec-1989 | 130.24 | 138.7 |
| Nov-1989 | 117.38 | 122.77 |
| Oct-1989 | 124.54 | 118.38 |
| Sep-1989 | 138.69 | 128.54 |
| Aug-1989 | 147.36 | 146.94 |
| Jul-1989 | 141 | 141.44 |
| Jun-1989 | 138.43 | 140.14 |
| May-1989 | 136.23 | 135.45 |
| Apr-1989 | 142.55 | 140.08 |
| Mar-1989 | 130.64 | 135.96 |
| Feb-1989 | 140.68 | 127.17 |
| Jan-1989 | 145.7 | 142.84 |
| Dec-1988 | 140.91 | 145.54 |
| Nov-1988 | 140.87 | 137.31 |
| Oct-1988 | 126.06 | 133.21 |
| Sep-1988 | 110.13 | 113.99 |
| Aug-1988 | 99.9 | 118.1 |
| Jul-1988 | 96.59 | 96.27 |
| Jun-1988 | 97.77 | 96.96 |
| May-1988 | 101.56 | 99.7 |
| Apr-1988 | 101.74 | 100.38 |
| Mar-1988 | 100.62 | 99.84 |
| Feb-1988 | 104.62 | 101.62 |
| Jan-1988 | 127.95 | 118.1 |
| Dec-1987 | 131.11 | 124.97 |
| Nov-1987 | 136.83 | 142.82 |
| Oct-1987 | 106.85 | 137.32 |
| Sep-1987 | 74.88 | 79.51 |
| Aug-1987 | 62.91 | 73.88 |
| Jul-1987 | 46.16 | 49.85 |
| Jun-1987 | 37 | 39.11 |
| May-1987 | 32.81 | 33.51 |
| Apr-1987 | 32.04 | 32.41 |
| Mar-1987 | 29.18 | 30.97 |
| Feb-1987 | 27.97 | 23.96 |
| Jan-1987 | 23.38 | 24.01 |
| Dec-1986 | 19.15 | 23.89 |
| Nov-1986 | 16.33 | 18.22 |
| Oct-1986 | 12.93 | 14.12 |
| Sep-1986 | 11.97 | 12.33 |
| Aug-1986 | 11.83 | 11.12 |
| Jul-1986 | 11.79 | 12.5 |
| Jun-1986 | 11.1 | 11.53 |
| May-1986 | 7.81 | 8.9 |
| Apr-1986 | 6.6 | 7.09 |
| Mar-1986 | 5.41 | 6.19 |
| Feb-1986 | 5.98 | 5.34 |
| Jan-1986 | 5.98 | 6.66 |
| Dec-1985 | 4.97 | 4.97 |
| Nov-1985 | 4.81 | 4.72 |
| Oct-1985 | 4.95 | 4.61 |
| Sep-1985 | 5.1 | 5.09 |
| Aug-1985 | 4.78 | 5.05 |
| Jul-1985 | 4.32 | 4.37 |
| Jun-1985 | 4.31 | 4.29 |
| May-1985 | 4.52 | 4.37 |
| Apr-1985 | 4.8 | 4.74 |
| Mar-1985 | 4.88 | 4.85 |
| Feb-1985 | 3.9 | 4.4 |
| Jan-1985 | 2.84 | 3.22 |
| Dec-1984 | 2.38 | 2.44 |
| Nov-1984 | 2.1 | 2.16 |
| Oct-1984 | 2.16 | 2.09 |
| Sep-1984 | 1.92 | 2 |
| Aug-1984 | 1.73 | 1.84 |
| Jul-1984 | 1.64 | 1.66 |
| Jun-1984 | 1.65 | 1.66 |
| May-1984 | 1.6 | 1.62 |
| Apr-1984 | 1.55 | 1.58 |
| Mar-1984 | 1.52 | 1.49 |
| Feb-1984 | 1.66 | 1.61 |
| Jan-1984 | 1.56 | 1.6 |
| Dec-1983 | 1.49 | 1.51 |
| Nov-1983 | 1.44 | 1.45 |
| Oct-1983 | 1.4 | 1.41 |
| Sep-1983 | 1.34 | 1.33 |
| Aug-1983 | 1.29 | 1.32 |
| Jul-1983 | 1.2 | 1.26 |
| Jun-1983 | 1.17 | 1.17 |
| May-1983 | 1.15 | 1.17 |
| Apr-1983 | 1.14 | 1.15 |
| Mar-1983 | 1.14 | 1.14 |
| Feb-1983 | 1.1 | 1.11 |
| Jan-1983 | 1.05 | 1.09 |
| Dec-1982 | 1.08 | 1.05 |
| Nov-1982 | 1.19 | 1.11 |
| Oct-1982 | 1.18 | 1.17 |
| Sep-1982 | 1.29 | 1.15 |
| Aug-1982 | 1.4 | 1.29 |
| Jul-1982 | 1.42 | 1.41 |
| Jun-1982 | 1.41 | 1.41 |
| May-1982 | 1.36 | 1.37 |
| Apr-1982 | 1.36 | 1.36 |
| Mar-1982 | 1.33 | 1.36 |
| Feb-1982 | 1.33 | 1.34 |
| Jan-1982 | 1.29 | 1.31 |
| Dec-1981 | 1.27 | 1.27 |
| Nov-1981 | 1.27 | 1.26 |
| Oct-1981 | 1.27 | 1.26 |
| Sep-1981 | 1.27 | 1.27 |
| Aug-1981 | 1.28 | 1.29 |
| Jul-1981 | 1.21 | 1.23 |
| Jun-1981 | 1.18 | 1.18 |
| May-1981 | 1.16 | 1.16 |
| Apr-1981 | 1.11 | 1.12 |
| Mar-1981 | 1.1 | 1.09 |
| Feb-1981 | 1.08 | 1.1 |
| Jan-1981 | 1.03 | 1.07 |
| Dec-1980 | 1.01 | 1 |
| Nov-1980 | 0.98 | 0.99 |
| Oct-1980 | 0.96 | 0.96 |
| Sep-1980 | 0.94 | 0.95 |
| Aug-1980 | 0.94 | 0.94 |
| Jul-1980 | 0.94 | 0.94 |
| Jun-1980 | 0.93 | 0.94 |
| May-1980 | 0.93 | 0.93 |
| Apr-1980 | 0.93 | 0.93 |
| Mar-1980 | 0.92 | 0.93 |
| Feb-1980 | 0.9 | 0.91 |
| Jan-1980 | 0.89 | 0.89 |
| Dec-1979 | 0.91 | 0.88 |
| Nov-1979 | 0.92 | 0.93 |
| Oct-1979 | 0.89 | 0.9 |
| Sep-1979 | 0.87 | 0.88 |
| Aug-1979 | 0.87 | 0.87 |
| Jul-1979 | 0.87 | 0.87 |
| Jun-1979 | 0.87 | 0.87 |
| May-1979 | 0.86 | 0.88 |
| Apr-1979 | 0.83 | 0.84 |
| Mar-1979 | 0.82 | 0.83 |
| Feb-1979 | 0.82 | 0.82 |
| Jan-1979 | 0.8 | 0.82 |
| Dec-1978 | 0.79 | 0.78 |
| Nov-1978 | 0.78 | 0.78 |
| Oct-1978 | 0.77 | 0.76 |
| Sep-1978 | 0.77 | 0.77 |
| Aug-1978 | 0.76 | 0.76 |
| Jul-1978 | 0.75 | 0.76 |
| Jun-1978 | 0.75 | 0.75 |
| May-1978 | 0.75 | 0.75 |
| Apr-1978 | 0.76 | 0.76 |
| Mar-1978 | 0.76 | 0.75 |
| Feb-1978 | 0.76 | 0.76 |
| Jan-1978 | 0.76 | 0.76 |
| Dec-1977 | 0.77 | 0.76 |
| Nov-1977 | 0.78 | 0.78 |
| Oct-1977 | 0.78 | 0.78 |
| Sep-1977 | 0.79 | 0.78 |
| Aug-1977 | 0.79 | 0.79 |
| Jul-1977 | 0.79 | 0.79 |
| Jun-1977 | 0.78 | 0.78 |
| May-1977 | 0.77 | 0.77 |
| Apr-1977 | 0.77 | 0.77 |
| Mar-1977 | 0.77 | 0.77 |
| Feb-1977 | 0.77 | 0.77 |
| Jan-1977 | 0.76 | 0.77 |
| Dec-1976 | 0.73 | 0.74 |
| Nov-1976 | 0.72 | 0.7 |
| Oct-1976 | 0.8 | 0.76 |
| Sep-1976 | 0.83 | 0.84 |
| Aug-1976 | 0.83 | 0.84 |
| Jul-1976 | 0.8 | 0.81 |
| Jun-1976 | 0.76 | 0.78 |
| May-1976 | 0.7 | 0.73 |
| Apr-1976 | 0.66 | 0.67 |
| Mar-1976 | 0.63 | 0.66 |
| Feb-1976 | 0.62 | 0.62 |
| Jan-1976 | 0.61 | 0.62 |
| Dec-1975 | 0.61 | 0.61 |
| Nov-1975 | 0.61 | 0.61 |
| Oct-1975 | 0.59 | 0.6 |
| Sep-1975 | 0.57 | 0.58 |
| Aug-1975 | 0.57 | 0.56 |
| Jul-1975 | 0.57 | 0.57 |
| Jun-1975 | 0.58 | 0.58 |
| May-1975 | 0.58 | 0.58 |
| Apr-1975 | 0.58 | 0.58 |
| Mar-1975 | 0.58 | 0.59 |
| Feb-1975 | 0.59 | 0.57 |
| Jan-1975 | 0.59 | 0.58 |
| Dec-1974 | 0.59 | 0.58 |
| Nov-1974 | 0.6 | 0.59 |
| Oct-1974 | 0.57 | 0.58 |
| Sep-1974 | 0.57 | 0.57 |
| Aug-1974 | 0.58 | 0.58 |
| Jul-1974 | 0.57 | 0.58 |
| Jun-1974 | 0.58 | 0.58 |
| May-1974 | 0.59 | 0.59 |
| Apr-1974 | 0.58 | 0.6 |
| Mar-1974 | 0.61 | 0.6 |
| Feb-1974 | 0.61 | 0.61 |
| Jan-1974 | 0.63 | 0.62 |
| Dec-1973 | 0.64 | 0.64 |
| Nov-1973 | 0.65 | 0.65 |
| Oct-1973 | 0.64 | 0.64 |
| Sep-1973 | 0.64 | 0.64 |
| Aug-1973 | 0.64 | 0.64 |
| Jul-1973 | 0.6 | 0.62 |
| Jun-1973 | 0.63 | 0.61 |
| May-1973 | 0.65 | 0.64 |
| Apr-1973 | 0.68 | 0.66 |
| Mar-1973 | 0.68 | 0.68 |
| Feb-1973 | 0.7 | 0.7 |
| Jan-1973 | 0.69 | 0.69 |
| Dec-1972 | 0.69 | 0.69 |
| Nov-1972 | 0.69 | 0.69 |
| Oct-1972 | 0.69 | 0.69 |
| Sep-1972 | 0.68 | 0.69 |
| Aug-1972 | 0.68 | 0.68 |
| Jul-1972 | 0.68 | 0.68 |
| Jun-1972 | 0.69 | 0.69 |
| May-1972 | 0.7 | 0.7 |
| Apr-1972 | 0.7 | 0.7 |
| Mar-1972 | 0.71 | 0.7 |
| Feb-1972 | 0.72 | 0.72 |
| Jan-1972 | 0.72 | 0.72 |
| Dec-1971 | 0.68 | 0.72 |
| Nov-1971 | 0.67 | 0.67 |
| Oct-1971 | 0.67 | 0.67 |
| Sep-1971 | 0.67 | 0.67 |
| Aug-1971 | 0.68 | 0.68 |
| Jul-1971 | 0.69 | 0.69 |
| Jun-1971 | 0.69 | 0.69 |
| May-1971 | 0.69 | 0.69 |
| Apr-1971 | 0.69 | 0.69 |
| Mar-1971 | 0.68 | 0.69 |
| Feb-1971 | 0.68 | 0.68 |
| Jan-1971 | 0.68 | 0.68 |
| Dec-1970 | 0.68 | 0.68 |
| Nov-1970 | 0.68 | 0.68 |
| Oct-1970 | 0.68 | 0.68 |
| Sep-1970 | 0.69 | 0.69 |
| Aug-1970 | 0.69 | 0.69 |
| Jul-1970 | 0.69 | 0.69 |
| Jun-1970 | 0.69 | 0.69 |
| May-1970 | 0.69 | 0.69 |
| Apr-1970 | 0.69 | 0.69 |
| Mar-1970 | 0.69 | 0.69 |
| Feb-1970 | 0.69 | 0.69 |
| Jan-1970 | 0.69 | 0.69 |
| Dec-1969 | 0.68 | 0.68 |
| Nov-1969 | 0.68 | 0.68 |
| Oct-1969 | 0.68 | 0.68 |
| Sep-1969 | 0.69 | 0.69 |
| Aug-1969 | 0.68 | 0.68 |
| Jul-1969 | 0.68 | 0.68 |
| Jun-1969 | 0.69 | 0.68 |
| May-1969 | 0.7 | 0.7 |
| Apr-1969 | 0.69 | 0.7 |
| Mar-1969 | 0.68 | 0.69 |
| Feb-1969 | 0.68 | 0.68 |
| Jan-1969 | 0.67 | 0.68 |
| Dec-1968 | 0.67 | 0.67 |
| Nov-1968 | 0.67 | 0.67 |
| Oct-1968 | 0.67 | 0.67 |
| Sep-1968 | 0.67 | 0.67 |
| Aug-1968 | 0.67 | 0.67 |
| Jul-1968 | 0.66 | 0.67 |
| Jun-1968 | 0.66 | 0.66 |
| May-1968 | 0.66 | 0.66 |
| Apr-1968 | 0.66 | 0.66 |
| Mar-1968 | 0.66 | 0.66 |
| Feb-1968 | 0.66 | 0.66 |
| Jan-1968 | 0.66 | 0.66 |
| Dec-1967 | 0.66 | 0.66 |
| Nov-1967 | 0.67 | 0.67 |
| Oct-1967 | 0.68 | 0.68 |
| Sep-1967 | 0.68 | 0.68 |
| Aug-1967 | 0.68 | 0.68 |
| Jul-1967 | 0.68 | 0.68 |
| Jun-1967 | 0.68 | 0.68 |
| May-1967 | 0.67 | 0.68 |
| Apr-1967 | 0.67 | 0.67 |
| Mar-1967 | 0.67 | 0.67 |
| Feb-1967 | 0.67 | 0.67 |
| Jan-1967 | 0.67 | 0.67 |
| Dec-1966 | 0.67 | 0.67 |
| Nov-1966 | 0.67 | 0.67 |
| Oct-1966 | 0.66 | 0.67 |
| Sep-1966 | 0.67 | 0.67 |
| Aug-1966 | 0.66 | 0.67 |
| Jul-1966 | 0.66 | 0.66 |
| Jun-1966 | 0.65 | 0.65 |
| May-1966 | 0.65 | 0.66 |
| Apr-1966 | 0.65 | 0.65 |
| Mar-1966 | 0.65 | 0.65 |
| Feb-1966 | 0.65 | 0.65 |
| Jan-1966 | 0.65 | 0.65 |
| Dec-1965 | 0 | 0 |
| Nov-1965 | 0 | 0 |
| Oct-1965 | 0 | 0 |
| Sep-1965 | 0 | 0 |
| Aug-1965 | 0 | 0 |
| Jul-1965 | 0 | 0 |
| Jun-1965 | 0 | 0 |
| May-1965 | 0 | 0 |
| Apr-1965 | 0 | 0 |
| Mar-1965 | 0 | 0 |
| Feb-1965 | 0 | 0 |
| Jan-1965 | 0 | 0 |
| Dec-1964 | 0 | 0 |
| Nov-1964 | 0 | 0 |
| Oct-1964 | 0 | 0 |
| Sep-1964 | 0 | 0 |
| Aug-1964 | 0 | 0 |
| Jul-1964 | 0 | 0 |
| Jun-1964 | 0 | 0 |
| May-1964 | 0 | 0 |
| Apr-1964 | 0 | 0 |
| Mar-1964 | 0 | 0 |
| Feb-1964 | 0 | 0 |
| Jan-1964 | 0 | 0 |