Year | Value | 2021 | 8.986 | 2020 | 8.076 | 2019 | 7.943 | 2018 | 6.935 | 2017 | 6.84 | 2016 | 6.717 | 2015 | 6.724 | 2014 | 6.483 | 2013 | 6.49 | 2012 | 6.491 | 2011 | 6.454 | 2010 | 6.269 | 2009 | 6.257 | 2008 | 6.128 | 2007 | 6.024 | 2006 | 5.853 | 2005 | 5.818 | 2004 | 5.835 | 2003 | 5.791 | 2002 | 5.785 | 2001 | 5.757 | 2000 | 5.706 | 1999 | 5.74 | 1998 | 5.81 | 1997 | 5.908 | 1996 | 5.985 | 1995 | 5.91 | 1994 | 5.814 | 1993 | 5.861 | 1992 | 5.799 | 1991 | 6.135 | 1990 | 5.855 | 1989 | 6.027 | 1988 | 6.14 | 1987 | 6.225 | 1986 | 6.036 | 1985 | 5.996 | 1984 | 5.903 | 1983 | 5.916 | 1982 | 6.14 | 1981 | 6.354 | 1980 | 6.362 | 1979 | 6.349 | 1978 | 6.196 | 1977 | 6.006 | 1976 | 5.951 | 1975 | 6.131 | 1974 | 6.206 | 1973 | 6.401 | 1972 | 6.427 | 1971 | 6.53 | 1970 | 6.637 | 1969 | 6.741 | 1968 | 6.859 | 1967 | 7.007 | 1966 | 7.117 | 1965 | 7.235 | 1964 | 7.358 | 1963 | 7.602 | 1962 | 7.855 | 1961 | 8.098 | 1960 | 8.353 |
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