Year | Value | 2021 | 8.009 | 2020 | 7.821 | 2019 | 7.811 | 2018 | 7.99 | 2017 | 8.242 | 2016 | 8.555 | 2015 | 8.826 | 2014 | 9.181 | 2013 | 9.607 | 2012 | 10.031 | 2011 | 10.63 | 2010 | 11.177 | 2009 | 11.788 | 2008 | 12.478 | 2007 | 13.133 | 2006 | 13.943 | 2005 | 14.497 | 2004 | 15.151 | 2003 | 15.804 | 2002 | 17.275 | 2001 | 17.789 | 2000 | 18.287 | 1999 | 18.701 | 1998 | 19.106 | 1997 | 18.367 | 1996 | 18.635 | 1995 | 18.826 | 1994 | 20.352 | 1993 | 21.41 | 1992 | 21.634 | 1991 | 20.475 | 1990 | 21.993 | 1989 | 22.161 | 1988 | 22.387 | 1987 | 22.934 | 1986 | 21.429 | 1985 | 21.576 | 1984 | 21.788 | 1983 | 21.979 | 1982 | 21.247 | 1981 | 21.462 | 1980 | 21.71 | 1979 | 21.936 | 1978 | 22.227 | 1977 | 22.571 | 1976 | 22.842 | 1975 | 22.884 | 1974 | 22.61 | 1973 | 23.004 | 1972 | 23.436 | 1971 | 23.906 | 1970 | 24.407 | 1969 | 24.824 | 1968 | 25.192 | 1967 | 25.58 | 1966 | 25.92 | 1965 | 26.205 | 1964 | 26.582 | 1963 | 26.913 | 1962 | 27.211 | 1961 | 27.483 | 1960 | 26.659 |
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