Year | Value | 2021 | 7.233 | 2020 | 6.831 | 2019 | 6.888 | 2018 | 7.012 | 2017 | 7.163 | 2016 | 7.343 | 2015 | 7.549 | 2014 | 7.579 | 2013 | 7.644 | 2012 | 7.747 | 2011 | 7.895 | 2010 | 7.951 | 2009 | 7.987 | 2008 | 8.096 | 2007 | 8.274 | 2006 | 8.504 | 2005 | 8.796 | 2004 | 9.065 | 2003 | 9.342 | 2002 | 9.604 | 2001 | 9.884 | 2000 | 10.187 | 1999 | 17.983 | 1998 | 15.703 | 1997 | 15.372 | 1996 | 15.81 | 1995 | 16.323 | 1994 | 16.121 | 1993 | 16.774 | 1992 | 17.472 | 1991 | 18.434 | 1990 | 18.691 | 1989 | 19.077 | 1988 | 26.634 | 1987 | 26.729 | 1986 | 28.068 | 1985 | 28.543 | 1984 | 28.423 | 1983 | 30.635 | 1982 | 31.347 | 1981 | 32.474 | 1980 | 33.565 | 1979 | 42.273 | 1978 | 43.774 | 1977 | 39.866 | 1976 | 37.854 | 1975 | 39.775 | 1974 | 24.954 | 1973 | 23.22 | 1972 | 23.964 | 1971 | 24.635 | 1970 | 25.261 | 1969 | 25.776 | 1968 | 26.317 | 1967 | 26.857 | 1966 | 27.641 | 1965 | 28.337 | 1964 | 29.165 | 1963 | 29.542 | 1962 | 29.853 | 1961 | 30.225 | 1960 | 30.571 |
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