Year | Value | 2021 | 6.845 | 2020 | 6.509 | 2019 | 6.416 | 2018 | 6.629 | 2017 | 6.082 | 2016 | 6.052 | 2015 | 6.137 | 2014 | 5.566 | 2013 | 5.507 | 2012 | 5.582 | 2011 | 5.554 | 2010 | 5.602 | 2009 | 5.651 | 2008 | 5.77 | 2007 | 5.954 | 2006 | 6.208 | 2005 | 6.413 | 2004 | 6.662 | 2003 | 6.898 | 2002 | 7.203 | 2001 | 7.565 | 2000 | 7.94 | 1999 | 8.306 | 1998 | 8.666 | 1997 | 8.932 | 1996 | 9.343 | 1995 | 9.642 | 1994 | 10.104 | 1993 | 10.236 | 1992 | 10.562 | 1991 | 10.878 | 1990 | 11.198 | 1989 | 11.588 | 1988 | 11.981 | 1987 | 12.484 | 1986 | 14.067 | 1985 | 13.592 | 1984 | 14.221 | 1983 | 15.009 | 1982 | 16.108 | 1981 | 16.739 | 1980 | 17.608 | 1979 | 18.569 | 1978 | 19.391 | 1977 | 20.342 | 1976 | 21.245 | 1975 | 22.125 | 1974 | 22.951 | 1973 | 23.866 | 1972 | 24.718 | 1971 | 25.58 | 1970 | 26.538 | 1969 | 27.538 | 1968 | 29.151 | 1967 | 30.091 | 1966 | 30.847 | 1965 | 31.544 | 1964 | 32.144 | 1963 | 33.593 | 1962 | 33.206 | 1961 | 32.711 | 1960 | 33.038 |
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