Year | Value | 2021 | 8.661 | 2020 | 8.442 | 2019 | 7.451 | 2018 | 6.938 | 2017 | 6.857 | 2016 | 6.925 | 2015 | 7.07 | 2014 | 7.168 | 2013 | 7.149 | 2012 | 7.038 | 2011 | 6.892 | 2010 | 6.758 | 2009 | 6.75 | 2008 | 6.74 | 2007 | 6.814 | 2006 | 6.705 | 2005 | 6.599 | 2004 | 6.408 | 2003 | 6.268 | 2002 | 6.046 | 2001 | 6.119 | 2000 | 5.876 | 1999 | 5.904 | 1998 | 6.087 | 1997 | 6.14 | 1996 | 6.314 | 1995 | 6.478 | 1994 | 6.556 | 1993 | 6.702 | 1992 | 6.929 | 1991 | 7.257 | 1990 | 7.812 | 1989 | 9.062 | 1988 | 8.35 | 1987 | 9.151 | 1986 | 10.059 | 1985 | 10.464 | 1984 | 11.596 | 1983 | 13.026 | 1982 | 13.772 | 1981 | 15.424 | 1980 | 15.815 | 1979 | 13.339 | 1978 | 12.892 | 1977 | 12.637 | 1976 | 12.491 | 1975 | 12.543 | 1974 | 12.826 | 1973 | 13.318 | 1972 | 14.035 | 1971 | 14.668 | 1970 | 15.396 | 1969 | 15.779 | 1968 | 15.959 | 1967 | 16.031 | 1966 | 16.061 | 1965 | 16.189 | 1964 | 16.335 | 1963 | 16.616 | 1962 | 16.923 | 1961 | 17.45 | 1960 | 17.996 |
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