Year | Value | 2023 | 7.077 | 2022 | 7.539 | 2021 | 8.366 | 2020 | 7.502 | 2019 | 6.452 | 2018 | 6.337 | 2017 | 6.256 | 2016 | 6.226 | 2015 | 6.045 | 2014 | 5.998 | 2013 | 5.924 | 2012 | 5.881 | 2011 | 5.843 | 2010 | 5.801 | 2009 | 5.784 | 2008 | 5.778 | 2007 | 5.793 | 2006 | 5.836 | 2005 | 5.896 | 2004 | 5.96 | 2003 | 6.033 | 2002 | 6.126 | 2001 | 6.189 | 2000 | 6.248 | 1999 | 6.302 | 1998 | 6.355 | 1997 | 6.393 | 1996 | 6.46 | 1995 | 6.54 | 1994 | 6.621 | 1993 | 6.713 | 1992 | 6.788 | 1991 | 6.879 | 1990 | 6.977 | 1989 | 7.092 | 1988 | 7.213 | 1987 | 7.359 | 1986 | 7.521 | 1985 | 7.689 | 1984 | 7.869 | 1983 | 8.053 | 1982 | 8.232 | 1981 | 8.414 | 1980 | 8.592 | 1979 | 8.771 | 1978 | 8.941 | 1977 | 9.117 | 1976 | 9.288 | 1975 | 9.463 |
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