Year | Value | 2021 | 74.36 | 2020 | 76.22 | 2019 | 76.98 | 2018 | 76.72 | 2017 | 76.78 | 2016 | 76.46 | 2015 | 76.25 | 2014 | 76.37 | 2013 | 76.22 | 2012 | 76.02 | 2011 | 75.88 | 2010 | 75.5 | 2009 | 74.86 | 2008 | 74.28 | 2007 | 74.22 | 2006 | 74.06 | 2005 | 73.97 | 2004 | 74.05 | 2003 | 74.06 | 2002 | 74.13 | 2001 | 73.63 | 2000 | 73.53 | 1999 | 73.61 | 1998 | 73.84 | 1997 | 73.19 | 1996 | 72.8 | 1995 | 72.54 | 1994 | 72.95 | 1993 | 73.35 | 1992 | 73.98 | 1991 | 74.21 | 1990 | 74.82 | 1989 | 75.16 | 1988 | 74.8 | 1987 | 74.9 | 1986 | 74.485 | 1985 | 73.375 | 1984 | 73.596 | 1983 | 73.912 | 1982 | 74.034 | 1981 | 73.672 | 1980 | 73.363 | 1979 | 73.418 | 1978 | 73.633 | 1977 | 73.583 | 1976 | 73.564 | 1975 | 73.611 | 1974 | 73.175 | 1973 | 73.155 | 1972 | 72.979 | 1971 | 73.101 | 1970 | 72.905 | 1969 | 72.961 | 1968 | 73.386 | 1967 | 73.235 | 1966 | 73.135 | 1965 | 73.275 | 1964 | 73.565 | 1963 | 73.232 | 1962 | 72.586 | 1961 | 72.812 | 1960 | 72.612 |
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