Year | Value | 2021 | 76.625053151771 | 2020 | 76.960093929662 | 2019 | 78.186595399875 | 2018 | 77.911987231714 | 2017 | 77.779873051013 | 2016 | 77.566878184282 | 2015 | 77.232245035164 | 2014 | 77.297204660985 | 2013 | 76.98637797055 | 2012 | 76.643309489055 | 2011 | 76.458476773037 | 2010 | 75.98639222958 | 2009 | 75.701708671069 | 2008 | 75.312822923357 | 2007 | 75.051362192626 | 2006 | 74.693193524823 | 2005 | 74.194628981064 | 2004 | 74.054543072274 | 2003 | 73.613451462979 | 2002 | 73.502903865998 | 2001 | 73.392599245853 | 2000 | 73.132089876572 | 1999 | 72.889937323611 | 1998 | 72.940144570014 | 1997 | 72.630438888256 | 1996 | 72.22507732871 | 1995 | 71.795317762704 | 1994 | 71.703513424703 | 1993 | 71.532493458379 | 1992 | 71.890679055825 | 1991 | 72.169251285159 | 1990 | 72.225918298236 | 1989 | 72.240195936732 | 1988 | 72.115383492582 | 1987 | 72.027134947584 | 1986 | 71.803413629598 | 1985 | 71.230651951537 | 1984 | 71.030841059611 | 1983 | 70.908507031313 | 1982 | 70.865354462709 | 1981 | 70.559195892168 | 1980 | 70.271023812869 | 1979 | 70.139312087803 | 1978 | 70.025291321929 | 1977 | 69.953336427261 | 1976 | 69.744609405811 | 1975 | 69.617363139763 | 1974 | 69.663856246767 | 1973 | 69.448088146961 | 1972 | 69.330653602616 | 1971 | 69.107238416461 | 1970 | 68.910748829567 | 1969 | 68.434637358077 | 1968 | 68.640342154879 | 1967 | 68.663130898044 | 1966 | 68.653129606736 | 1965 | 68.465783243882 | 1964 | 68.480946065944 | 1963 | 67.959076782945 | 1962 | 67.624774376947 | 1961 | 67.751046510269 | 1960 | 67.478571910639 |
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