Year | Value | 2021 | 8.42 | 2020 | 8.611 | 2019 | 8.819 | 2018 | 9.067 | 2017 | 9.02 | 2016 | 8.953 | 2015 | 8.842 | 2014 | 8.768 | 2013 | 8.949 | 2012 | 9.211 | 2011 | 8.878 | 2010 | 9.492 | 2009 | 9.851 | 2008 | 9.835 | 2007 | 9.794 | 2006 | 9.374 | 2005 | 9.582 | 2004 | 9.842 | 2003 | 9.86 | 2002 | 9.902 | 2001 | 9.816 | 2000 | 10.068 | 1999 | 10.556 | 1998 | 11.791 | 1997 | 12.296 | 1996 | 11.221 | 1995 | 10.698 | 1994 | 11.548 | 1993 | 12.524 | 1992 | 14.411 | 1991 | 14.75 | 1990 | 14.912 | 1989 | 15.318 | 1988 | 15.921 | 1987 | 16.39 | 1986 | 16.867 | 1985 | 17.406 | 1984 | 17.888 | 1983 | 18.17 | 1982 | 18.24 | 1981 | 17.945 | 1980 | 17.492 | 1979 | 17.359 | 1978 | 17.676 | 1977 | 18.168 | 1976 | 18.8 | 1975 | 19.336 | 1974 | 19.866 | 1973 | 20.454 | 1972 | 21.119 | 1971 | 21.586 | 1970 | 21.978 | 1969 | 22.724 | 1968 | 23.474 | 1967 | 24.447 | 1966 | 25.611 | 1965 | 26.884 | 1964 | 28.006 | 1963 | 29.247 | 1962 | 30.401 | 1961 | 31.475 | 1960 | 32.36 |
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