Year years 1960 53.033929595941366 1961 53.5675026503092 1962 54.00462010289061 1963 54.41907095497933 1964 54.90603864749979 1965 55.25596291670395 1966 55.67789499539063 1967 56.046794473470406 1968 56.398054577559996 1969 56.7351388183295 1970 56.831374668985994 1971 57.57385522344595 1972 57.90013353785445 1973 58.401813578761406 1974 58.81665772453342 1975 59.28102816530213 1976 59.4869848000215 1977 59.94777413667709 1978 60.24946223234798 1979 60.5536231133381 1980 60.969517283730475 1981 61.4053848860379 1982 61.70092801452073 1983 62.268351346513775 1984 62.662248967827296 1985 63.02614311584132 1986 63.57742400148757 1987 63.959977157737384 1988 64.35107202779338 1989 64.61736036216747 1990 64.80132520091954 1991 65.13153305776702 1992 65.44495596482874 1993 65.75224116353697 1994 66.15067847272597 1995 66.42679240729542 1996 66.80346664280694 1997 67.15441559521383 1998 67.43482746217563 1999 67.82645112522039 2000 68.03337855082769 2001 68.2743362972536 2002 68.63923351544241 2003 68.89394087619756 2004 69.2030756419444 2005 69.60043648219539 2006 69.81021271804673 2007 69.95423474716405 2008 70.1870985922257 2009 70.4090178704184 2010 70.31848917430489 2011 70.80267829899799 2012 71.00934495636179 2013 71.30562424076817 2014 71.54183140931468 2015 71.56110720348259 2016 71.46214057162534 2017 71.68474662465204 2018 71.77989868934326 2019 71.95428487524686 2020 69.67003212114447 2021 68.8040106136205 2022 70.64912698818006