Year | Value | 2021 | 6.729 | 2020 | 6.424 | 2019 | 6.309 | 2018 | 6.353 | 2017 | 6.504 | 2016 | 6.58 | 2015 | 6.654 | 2014 | 6.806 | 2013 | 6.998 | 2012 | 7.08 | 2011 | 7.249 | 2010 | 7.492 | 2009 | 7.685 | 2008 | 7.989 | 2007 | 8.192 | 2006 | 8.439 | 2005 | 8.908 | 2004 | 9.242 | 2003 | 9.431 | 2002 | 9.727 | 2001 | 9.954 | 2000 | 11.084 | 1999 | 18.754 | 1998 | 14.821 | 1997 | 11.263 | 1996 | 11.635 | 1995 | 12.022 | 1994 | 12.528 | 1993 | 13.035 | 1992 | 13.545 | 1991 | 14.627 | 1990 | 15.215 | 1989 | 16.507 | 1988 | 16.435 | 1987 | 16.916 | 1986 | 17.161 | 1985 | 17.794 | 1984 | 18.084 | 1983 | 18.427 | 1982 | 18.762 | 1981 | 18.775 | 1980 | 19.024 | 1979 | 19.463 | 1978 | 19.812 | 1977 | 20.153 | 1976 | 20.598 | 1975 | 20.967 | 1974 | 21.052 | 1973 | 21.146 | 1972 | 21.551 | 1971 | 21.936 | 1970 | 22.336 | 1969 | 22.706 | 1968 | 23.068 | 1967 | 23.373 | 1966 | 23.59 | 1965 | 23.895 | 1964 | 24.178 | 1963 | 24.593 | 1962 | 24.93 | 1961 | 25.289 | 1960 | 25.715 |
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