| Year | Value | | 2022 | 72.224 | | 2021 | 71.56 | | 2020 | 70.877 | | 2019 | 70.172 | | 2018 | 69.446 | | 2017 | 68.7 | | 2016 | 67.933 | | 2015 | 67.155 | | 2014 | 66.368 | | 2013 | 65.572 | | 2012 | 64.768 | | 2011 | 63.865 | | 2010 | 62.412 | | 2009 | 60.937 | | 2008 | 59.444 | | 2007 | 57.928 | | 2006 | 56.4 | | 2005 | 55.944 | | 2004 | 55.488 | | 2003 | 55.029 | | 2002 | 54.57 | | 2001 | 54.062 | | 2000 | 53.219 | | 1999 | 52.372 | | 1998 | 51.525 | | 1997 | 50.677 | | 1996 | 49.83 | | 1995 | 48.981 | | 1994 | 48.133 | | 1993 | 47.286 | | 1992 | 46.443 | | 1991 | 45.292 | | 1990 | 41.933 | | 1989 | 38.648 | | 1988 | 35.467 | | 1987 | 32.401 | | 1986 | 29.483 | | 1985 | 26.724 | | 1984 | 24.139 | | 1983 | 21.723 | | 1982 | 19.489 | | 1981 | 17.552 | | 1980 | 16.479 | | 1979 | 15.457 | | 1978 | 14.489 | | 1977 | 13.572 | | 1976 | 12.705 | | 1975 | 11.884 | | 1974 | 11.11 | | 1973 | 10.381 | | 1972 | 9.695 | | 1971 | 8.998 | | 1970 | 7.834 | | 1969 | 6.81 | | 1968 | 5.912 | | 1967 | 5.124 | | 1966 | 4.437 | | 1965 | 3.839 | | 1964 | 3.318 | | 1963 | 3.171 | | 1962 | 3.134 | | 1961 | 3.097 | | 1960 | 3.06 |
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