Year | Value | 2021 | 7.988 | 2020 | 7.327 | 2019 | 6.006 | 2018 | 6.103 | 2017 | 6.173 | 2016 | 6.318 | 2015 | 6.438 | 2014 | 6.612 | 2013 | 6.681 | 2012 | 6.791 | 2011 | 6.864 | 2010 | 6.895 | 2009 | 6.801 | 2008 | 6.605 | 2007 | 6.416 | 2006 | 6.177 | 2005 | 5.98 | 2004 | 5.838 | 2003 | 5.747 | 2002 | 5.707 | 2001 | 5.72 | 2000 | 5.782 | 1999 | 5.904 | 1998 | 6.056 | 1997 | 6.144 | 1996 | 6.217 | 1995 | 6.294 | 1994 | 6.323 | 1993 | 6.532 | 1992 | 6.753 | 1991 | 7.068 | 1990 | 7.243 | 1989 | 7.607 | 1988 | 7.996 | 1987 | 8.426 | 1986 | 8.876 | 1985 | 9.329 | 1984 | 9.837 | 1983 | 10.146 | 1982 | 10.397 | 1981 | 10.678 | 1980 | 11.033 | 1979 | 11.262 | 1978 | 11.509 | 1977 | 11.77 | 1976 | 12.013 | 1975 | 12.257 | 1974 | 12.524 | 1973 | 12.784 | 1972 | 12.93 | 1971 | 13.277 | 1970 | 18.756 | 1969 | 14.096 | 1968 | 14.456 | 1967 | 14.819 | 1966 | 15.166 | 1965 | 15.501 | 1964 | 15.781 | 1963 | 16.062 | 1962 | 16.549 | 1961 | 16.782 | 1960 | 17.229 |
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