Data Series
| Period | in Percent |
| Oct-2020 | 4.03 |
| Sep-2020 | 4.28 |
| Aug-2020 | 4.39 |
| Jul-2020 | 4.69 |
| Jun-2020 | 5.13 |
| May-2020 | 5.55 |
| Apr-2020 | 5.94 |
| Mar-2020 | 5.98 |
| Feb-2020 | 6.71 |
| Jan-2020 | 7.59 |
| Dec-2019 | 8.29 |
| Nov-2019 | 10.43 |
| Oct-2019 | 9.95 |
| Sep-2019 | 9.98 |
| Aug-2019 | 9.73 |
| Jul-2019 | 9.53 |
| Jun-2019 | 9.51 |
| May-2019 | 9.42 |
| Apr-2019 | 9.33 |
| Mar-2019 | 9.45 |
| Feb-2019 | 9.96 |
| Jan-2019 | 9.68 |
| Dec-2018 | 9.13 |
| Nov-2018 | 8.74 |
| Oct-2018 | 8.45 |
| Sep-2018 | 8.09 |
| Aug-2018 | 7.65 |
| Jul-2018 | 7.57 |
| Jun-2018 | 7.3 |
| May-2018 | 7.29 |
| Apr-2018 | 7.22 |
| Mar-2018 | 7.2 |
| Feb-2018 | 7.03 |
| Jan-2018 | 7.01 |
| Dec-2017 | 6.91 |
| Nov-2017 | 6.31 |
| Oct-2017 | 5.96 |
| Sep-2017 | 5.92 |
| Aug-2017 | 5.93 |
| Jul-2017 | 5.94 |
| Jun-2017 | 5.88 |
| May-2017 | 5.94 |
| Apr-2017 | 5.92 |
| Mar-2017 | 5.93 |
| Feb-2017 | 5.93 |
| Jan-2017 | 5.91 |
| Dec-2016 | 5.93 |
| Nov-2016 | 5.91 |
| Oct-2016 | 5.9 |
| Sep-2016 | 5.97 |
| Aug-2016 | 5.94 |
| Jul-2016 | 5.94 |
| Jun-2016 | 5.92 |
| May-2016 | 5.93 |
| Apr-2016 | 5.95 |
| Mar-2016 | 5.95 |
| Feb-2016 | 5.92 |
| Jan-2016 | 5.88 |
| Dec-2015 | 5.97 |
| Nov-2015 | 5.97 |
| Oct-2015 | 6.04 |
| Sep-2015 | 5.96 |
| Aug-2015 | 6 |
| Jul-2015 | 6 |
| Jun-2015 | 5.92 |
| May-2015 | 5.97 |
| Apr-2015 | 6.01 |
| Mar-2015 | 5.96 |
| Feb-2015 | 5.98 |
| Jan-2015 | 5.95 |
| Dec-2014 | 5.93 |
| Nov-2014 | 5.95 |
| Oct-2014 | 5.97 |
| Sep-2014 | 5.9 |
| Aug-2014 | 5.95 |
| Jul-2014 | 5.94 |
| Jun-2014 | 5.86 |
| May-2014 | 5.93 |
| Apr-2014 | 5.89 |
| Mar-2014 | 5.86 |
| Feb-2014 | 5.9 |
| Jan-2014 | 5.88 |
| Dec-2013 | 5.83 |
| Nov-2013 | 5.86 |
| Oct-2013 | 5.85 |
| Sep-2013 | 5.78 |
| Aug-2013 | 5.87 |
| Jul-2013 | 5.84 |
| Jun-2013 | 5.79 |
| May-2013 | 5.86 |
| Apr-2013 | 5.82 |
| Mar-2013 | 5.79 |
| Feb-2013 | 5.83 |
| Jan-2013 | 5.82 |
| Dec-2012 | 5.78 |
| Nov-2012 | 5.79 |
| Oct-2012 | 5.76 |
| Sep-2012 | 5.73 |
| Aug-2012 | 5.83 |
| Jul-2012 | 5.75 |
| Jun-2012 | 5.75 |
| May-2012 | 5.79 |
| Apr-2012 | 5.72 |
| Mar-2012 | 5.77 |
| Feb-2012 | 5.74 |
| Jan-2012 | 5.86 |
| Dec-2011 | 5.91 |
| Nov-2011 | 5.84 |
| Oct-2011 | 5.84 |
| Sep-2011 | 5.85 |
| Aug-2011 | 5.81 |
| Jul-2011 | 5.87 |
| Jun-2011 | 5.94 |
| May-2011 | 5.92 |
| Apr-2011 | 5.9 |
| Mar-2011 | 5.92 |
| Feb-2011 | 5.92 |
| Jan-2011 | 5.89 |
| Dec-2010 | 5.97 |
| Nov-2010 | 5.95 |
| Oct-2010 | 5.98 |
| Sep-2010 | 5.96 |
| Aug-2010 | 5.99 |
| Jul-2010 | 6.04 |
| Jun-2010 | 6.1 |
| May-2010 | 6.2 |
| Apr-2010 | 6.25 |
| Mar-2010 | 6.36 |
| Feb-2010 | 6.7 |
| Jan-2010 | 6.87 |
| Dec-2009 | 7.07 |
| Nov-2009 | 7.09 |
| Oct-2009 | 7.16 |
| Sep-2009 | 7.26 |
| Aug-2009 | 7.32 |
| Jul-2009 | 7.33 |
| Jun-2009 | 7.31 |
| May-2009 | 7.38 |
| Apr-2009 | 7.41 |
| Mar-2009 | 7.44 |
| Feb-2009 | 7.48 |
| Jan-2009 | 7.56 |
| Dec-2008 | 7.62 |
| Nov-2008 | 7.63 |
| Oct-2008 | 7.64 |
| Sep-2008 | 7.63 |
| Aug-2008 | 7.64 |
| Jul-2008 | 7.67 |
| Jun-2008 | 7.68 |
| May-2008 | 7.71 |
| Apr-2008 | 7.71 |
| Mar-2008 | 7.79 |
| Feb-2008 | 7.8 |
| Jan-2008 | 7.93 |
| Dec-2007 | 7.94 |
| Nov-2007 | 7.91 |
| Oct-2007 | 7.96 |
| Sep-2007 | 7.96 |
| Aug-2007 | 7.99 |
| Jul-2007 | 7.99 |
| Jun-2007 | 7.99 |
| May-2007 | 8.02 |
| Apr-2007 | 7.98 |
| Mar-2007 | 7.99 |
| Feb-2007 | 7.97 |
| Jan-2007 | 7.99 |
| Dec-2006 | 8.02 |
| Nov-2006 | 7.99 |
| Oct-2006 | 7.93 |
| Sep-2006 | 7.96 |
| Aug-2006 | 7.96 |
| Jul-2006 | 7.87 |
| Jun-2006 | 7.99 |
| May-2006 | 7.97 |
| Apr-2006 | 7.99 |
| Mar-2006 | 8.02 |
| Feb-2006 | 8.04 |
| Jan-2006 | 8.06 |
| Dec-2005 | 8.11 |
| Nov-2005 | 8.02 |
| Oct-2005 | 8.04 |
| Sep-2005 | 8.02 |
| Aug-2005 | 8.13 |
| Jul-2005 | 8.33 |
| Jun-2005 | 8.73 |
| May-2005 | 8.91 |
| Apr-2005 | 8.9 |
| Mar-2005 | 8.5 |
| Feb-2005 | 7.02 |
| Jan-2005 | 7.08 |
| Dec-2004 | 7.38 |
| Nov-2004 | 7.13 |
| Oct-2004 | 7.17 |
| Sep-2004 | 7.18 |
| Aug-2004 | 7.28 |
| Jul-2004 | 7.25 |
| Jun-2004 | 7.25 |
| May-2004 | 7.33 |
| Apr-2004 | 7.39 |
| Mar-2004 | 7.53 |
| Feb-2004 | 7.7 |
| Jan-2004 | 7.89 |
| Dec-2003 | 8.19 |
| Nov-2003 | 8.23 |
| Oct-2003 | 8.26 |
| Sep-2003 | 8.31 |
| Aug-2003 | 8.35 |
| Jul-2003 | 8.4 |
| Jun-2003 | 8.65 |
| May-2003 | 8.7 |
| Apr-2003 | 8.95 |
| Mar-2003 | 9.24 |
| Feb-2003 | 9.24 |
| Jan-2003 | 9.8 |
| Dec-2002 | 10.46 |
| Nov-2002 | 11.16 |
| Oct-2002 | 11.32 |
| Sep-2002 | 11.32 |
| Aug-2002 | 11.37 |
| Jul-2002 | 11.39 |
| Jun-2002 | 11.2 |
| May-2002 | 11.11 |
| Apr-2002 | 10.72 |
| Mar-2002 | 10.79 |
| Feb-2002 | 10.78 |
| Jan-2002 | 10.79 |
| Dec-2001 | 10.82 |
| Nov-2001 | 10.75 |
| Oct-2001 | 10.79 |
| Sep-2001 | 10.73 |
| Aug-2001 | 10.82 |
| Jul-2001 | 10.83 |
| Jun-2001 | 10.84 |
| May-2001 | 10.78 |
| Apr-2001 | 10.91 |
| Mar-2001 | 10.93 |
| Feb-2001 | 10.95 |
| Jan-2001 | 11.08 |
| Dec-2000 | 11.06 |
| Nov-2000 | 11.05 |
| Oct-2000 | 10.97 |
| Sep-2000 | 11.04 |
| Aug-2000 | 11.13 |
| Jul-2000 | 11.19 |
| Jun-2000 | 11.14 |
| May-2000 | 11.19 |
| Apr-2000 | 11.17 |
| Mar-2000 | 11.35 |
| Feb-2000 | 11.49 |
| Jan-2000 | 11.74 |
| Dec-1999 | 11.91 |
| Nov-1999 | 11.93 |
| Oct-1999 | 12 |
| Sep-1999 | 12.89 |
| Aug-1999 | 12.32 |
| Jul-1999 | 12.43 |
| Jun-1999 | 12.47 |
| May-1999 | 12.59 |
| Apr-1999 | 12.68 |
| Mar-1999 | 12.81 |
| Feb-1999 | 12.87 |
| Jan-1999 | 13.06 |
| Dec-1998 | 13.32 |
| Nov-1998 | 13.32 |
| Oct-1998 | 13.4 |
| Sep-1998 | 13.47 |
| Aug-1998 | 13.47 |
| Jul-1998 | 13.64 |
| Jun-1998 | 13.79 |
| May-1998 | 13.83 |
| Apr-1998 | 13.82 |
| Mar-1998 | 13.83 |
| Feb-1998 | 13.73 |
| Jan-1998 | 13.66 |
| Dec-1997 | 13.72 |
| Nov-1997 | 13.19 |
| Oct-1997 | 12.86 |
| Sep-1997 | 12.87 |
| Aug-1997 | 12.93 |
| Jul-1997 | 12.97 |
| Jun-1997 | 13.08 |
| May-1997 | 13.16 |
| Apr-1997 | 13.27 |
| Mar-1997 | 13.56 |
| Feb-1997 | 13.95 |
| Jan-1997 | 14.87 |
| Dec-1996 | 15.36 |
| Nov-1996 | 15.4 |
| Oct-1996 | 15.41 |
| Sep-1996 | 15.35 |
| Aug-1996 | 15.41 |
| Jul-1996 | 15.27 |
| Jun-1996 | 15.17 |
| May-1996 | 15.34 |
| Apr-1996 | 15.37 |
| Mar-1996 | 15.52 |
| Feb-1996 | 15.95 |
| Jan-1996 | 16.95 |
| Dec-1995 | 18.23 |
| Nov-1995 | 20.21 |
| Oct-1995 | 20.1 |
| Sep-1995 | 17.27 |
| Aug-1995 | 16.15 |
| Jul-1995 | 15.7 |
| Jun-1995 | 15.24 |
| May-1995 | 14.58 |
| Apr-1995 | 14.4 |
| Mar-1995 | 14.51 |
| Feb-1995 | 13.93 |
| Jan-1995 | 13.56 |
| Dec-1994 | 13.87 |
| Nov-1994 | 14.05 |
| Oct-1994 | 14.13 |
| Sep-1994 | 14.19 |
| Aug-1994 | 14.1 |
| Jul-1994 | 14.18 |
| Jun-1994 | 14.7 |
| May-1994 | 15.29 |
| Apr-1994 | 15.27 |
| Mar-1994 | 15.75 |
| Feb-1994 | 16.01 |
| Jan-1994 | 16.07 |
| Dec-1993 | 16.1 |
| Nov-1993 | 16.19 |
| Oct-1993 | 16.05 |
| Sep-1993 | 15.92 |
| Aug-1993 | 15.84 |
| Jul-1993 | 15.69 |
| Jun-1993 | 15.68 |
| May-1993 | 15.73 |
| Apr-1993 | 15.58 |
| Mar-1993 | 15.58 |
| Feb-1993 | 14.79 |
| Jan-1993 | 13.57 |
| Dec-1992 | 14.26 |
| Nov-1992 | 15.93 |
| Oct-1992 | 18.79 |
| Sep-1992 | 20.11 |
| Aug-1992 | 18.04 |
| Jul-1992 | 17.71 |
| Jun-1992 | 17.52 |
| May-1992 | 17.41 |
| Apr-1992 | 17.28 |
| Mar-1992 | 16.83 |
| Feb-1992 | 15.84 |
| Jan-1992 | 15.3 |
| Dec-1991 | 15.37 |
| Nov-1991 | 15.56 |
| Oct-1991 | 15.93 |
| Sep-1991 | 16.35 |
| Aug-1991 | 16.57 |
| Jul-1991 | 17.01 |
| Jun-1991 | 17.49 |
| May-1991 | 18 |
| Apr-1991 | 17.59 |
| Mar-1991 | 17.73 |
| Feb-1991 | 17.13 |
| Jan-1991 | 16.44 |
| Dec-1990 | 16.96 |
| Nov-1990 | 16.56 |
| Oct-1990 | 16.66 |
| Sep-1990 | 17.15 |
| Aug-1990 | 16.81 |
| Jul-1990 | 16.92 |
| Jun-1990 | 16.74 |
| May-1990 | 16.9 |
| Apr-1990 | 17 |
| Mar-1990 | 16.8 |
| Feb-1990 | 16.94 |
| Jan-1990 | 16.85 |
| Dec-1989 | 16.38 |
| Nov-1989 | 16.89 |
| Oct-1989 | 17.12 |
| Sep-1989 | 17.17 |
| Aug-1989 | 17.54 |
| Jul-1989 | 17.48 |
| Jun-1989 | 17.77 |
| May-1989 | 17.72 |
| Apr-1989 | 17.86 |
| Mar-1989 | 18.09 |
| Feb-1989 | 18.2 |
| Jan-1989 | 18.23 |
| Dec-1988 | 18.62 |
| Nov-1988 | 19.07 |
| Oct-1988 | 19.07 |
| Sep-1988 | 19.76 |
| Aug-1988 | 20.42 |
| Jul-1988 | 21.21 |
| Jun-1988 | 23.25 |
| May-1988 | 24.28 |
| Apr-1988 | 24.53 |
| Mar-1988 | 23.86 |
| Feb-1988 | 24.8 |
| Jan-1988 | 24.63 |
| Dec-1987 | 23.36 |
| Nov-1987 | 23.1 |
| Oct-1987 | 22.1 |
| Sep-1987 | 21.97 |
| Aug-1987 | 21.41 |
| Jul-1987 | 22.79 |
| Jun-1987 | 20.37 |
| May-1987 | 19.21 |
| Apr-1987 | 19.52 |
| Mar-1987 | 20.15 |
| Feb-1987 | 20.1 |
| Jan-1987 | 20.05 |
| Dec-1986 | 18.25 |
| Nov-1986 | 18.2 |
| Oct-1986 | 18.15 |
| Sep-1986 | 17.95 |
| Aug-1986 | 17.75 |
| Jul-1986 | 16.85 |
| Jun-1986 | 16.05 |
| May-1986 | 15.75 |
| Apr-1986 | 15.75 |
| Mar-1986 | 14.9 |
| Feb-1986 | 14.05 |
| Jan-1986 | 13.35 |
| Dec-1985 | 13.4 |
| Nov-1985 | 13.3 |
| Oct-1985 | 13 |
| Sep-1985 | 12.7 |
| Aug-1985 | 12.8 |
| Jul-1985 | 13.2 |
| Jun-1985 | 13.45 |
| May-1985 | 13.5 |
| Apr-1985 | 13.5 |
| Mar-1985 | 13.5 |
| Feb-1985 | 13.3 |
| Jan-1985 | 13.25 |
| Dec-1984 | 13 |
| Nov-1984 | 12.85 |
| Oct-1984 | 12.65 |
| Sep-1984 | 11.95 |
| Aug-1984 | 11.85 |
| Jul-1984 | 11.75 |
| Jun-1984 | 10.95 |
| May-1984 | 10.85 |
| Apr-1984 | 10.8 |
| Mar-1984 | 10.75 |
| Feb-1984 | 10.66 |
| Jan-1984 | 10.3 |
| Dec-1983 | 10.1 |
| Nov-1983 | 10.04 |
| Oct-1983 | 9.98 |
| Sep-1983 | 9.98 |
| Aug-1983 | 9.95 |
| Jul-1983 | 9.97 |
| Jun-1983 | 9.86 |
| May-1983 | 9.87 |
| Apr-1983 | 9.8 |
| Mar-1983 | 10 |
| Feb-1983 | 10 |
| Jan-1983 | 10.56 |
| Dec-1982 | 11.7 |
| Nov-1982 | 12.25 |
| Oct-1982 | 12.6 |
| Sep-1982 | 13.05 |
| Aug-1982 | 13.7 |
| Jul-1982 | 13.5 |
| Jun-1982 | 13.2 |
| May-1982 | 13.5 |
| Apr-1982 | 13.4 |
| Mar-1982 | 13.2 |
| Feb-1982 | 13 |
| Jan-1982 | 12.2 |
| Dec-1980 | 8.05 |
| Sep-1980 | 7.72 |
| Jun-1980 | 7.95 |
| Mar-1980 | 7.69 |
| Dec-1979 | 6.92 |
| Sep-1979 | 6.39 |
| Jun-1979 | 6.21 |
| Mar-1979 | 5.44 |
| Dec-1978 | 5.41 |
| Sep-1978 | 5.52 |
| Jun-1978 | 5.26 |
| Mar-1978 | 5.98 |
| Dec-1977 | 5.68 |
| Sep-1977 | 6.32 |
| Jun-1977 | 7.06 |
| Mar-1977 | 6.79 |
| Dec-1976 | 6.78 |
| Sep-1976 | 6.51 |
| Jun-1976 | 5.76 |
| Mar-1976 | 6.94 |
| Dec-1975 | 6.34 |
| Sep-1975 | 6.42 |
| Jun-1975 | 6.91 |
| Mar-1975 | 6.54 |
| Dec-1974 | 6.88 |
| Sep-1974 | 6.4 |
| Jun-1974 | 6.27 |
| Mar-1974 | 6.04 |
| Dec-1973 | 5.38 |
| Sep-1973 | 4.7 |
| Jun-1973 | 4.84 |
| Mar-1973 | 4.6 |
| Dec-1972 | 4.49 |
| Sep-1972 | 4.44 |
| Jun-1972 | 4.55 |
| Mar-1972 | 4.81 |