Year | Value | 2021 | 6.477 | 2020 | 6.545 | 2019 | 6.626 | 2018 | 6.766 | 2017 | 6.94 | 2016 | 6.837 | 2015 | 6.759 | 2014 | 6.705 | 2013 | 6.683 | 2012 | 6.689 | 2011 | 6.737 | 2010 | 6.808 | 2009 | 6.922 | 2008 | 7.009 | 2007 | 7.166 | 2006 | 7.353 | 2005 | 7.473 | 2004 | 7.498 | 2003 | 7.542 | 2002 | 7.669 | 2001 | 7.827 | 2000 | 8.368 | 1999 | 8.221 | 1998 | 8.529 | 1997 | 8.858 | 1996 | 9.189 | 1995 | 9.555 | 1994 | 10.024 | 1993 | 10.312 | 1992 | 10.699 | 1991 | 11.145 | 1990 | 11.543 | 1989 | 11.97 | 1988 | 12.426 | 1987 | 12.921 | 1986 | 13.431 | 1985 | 13.951 | 1984 | 14.444 | 1983 | 14.976 | 1982 | 15.535 | 1981 | 16.13 | 1980 | 16.732 | 1979 | 17.338 | 1978 | 17.959 | 1977 | 18.587 | 1976 | 19.252 | 1975 | 19.946 | 1974 | 20.637 | 1973 | 21.347 | 1972 | 22.114 | 1971 | 22.873 | 1970 | 23.621 | 1969 | 24.406 | 1968 | 25.235 | 1967 | 25.896 | 1966 | 26.556 | 1965 | 27.187 | 1964 | 27.775 | 1963 | 28.33 | 1962 | 28.86 | 1961 | 29.361 | 1960 | 29.82 |
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