Year years 1960 71.34069743713613 1961 71.7384098047086 1962 71.70120131260795 1963 72.04019737706702 1964 72.59403648908108 1965 72.67543924418598 1966 72.9885887179833 1967 73.22470451917808 1968 73.23419620206379 1969 73.27148759090468 1970 73.72676541036027 1971 74.0698092239585 1972 74.26770345820297 1973 74.4333233487298 1974 74.79427288447032 1975 75.02856598501657 1976 75.2395819979124 1977 75.63864151519908 1978 75.79210678460339 1979 76.08188004878808 1980 76.06576433172756 1981 76.41052716783713 1982 76.73589499819965 1983 76.78939578393849 1984 76.98976278702618 1985 77.10626683166868 1986 77.4247014480898 1987 77.6676685077239 1988 77.7942749658928 1989 77.98530432351954 1990 78.14788720764854 1991 78.2357748963448 1992 78.23287900786517 1993 78.16616005809396 1994 78.49455809849813 1995 78.50195844909841 1996 78.85140619874471 1997 79.14719868315322 1998 79.33051323139023 1999 79.32980799701009 2000 79.53370262209049 2001 79.76580957658258 2002 79.85695378848268 2003 79.93343289791484 2004 80.37530049447791 2005 80.47447950240561 2006 80.8510969256463 2007 81.11650228891872 2008 81.25767726615385 2009 81.56212539789892 2010 81.71322815815516 2011 82.02494287450375 2012 82.1135428044083 2013 82.3126538630111 2014 82.5473446702494 2015 82.44574070823813 2016 82.63969981232715 2017 82.70199488452428 2018 82.80418013856931 2019 83.03803339811563 2020 82.16609390357533 2021 81.77234402153233 2022 82.43549471752509