Year years 1960 43.54772370847069 1961 44.77693942343279 1962 45.04649115024914 1963 45.81835788165576 1964 46.519811532824214 1965 47.12926685111152 1966 48.08047971831471 1967 48.49931094477638 1968 48.94955096918828 1969 49.51731577302037 1970 50.09468165356264 1971 50.800066794285506 1972 51.38828408841877 1973 51.794215437756584 1974 52.62403709483008 1975 53.138841588117884 1976 53.67828343443398 1977 54.94456764146791 1978 55.48410042183101 1979 56.58439796136183 1980 56.63629980645243 1981 56.06225490896267 1982 56.428416583124815 1983 57.944662351002165 1984 59.461029812986766 1985 60.21587042020724 1986 60.665326456748495 1987 61.5276225384533 1988 61.888225704022716 1989 63.18469886490046 1990 63.19054258324229 1991 64.37549582227608 1992 65.00110394120011 1993 65.35389125719011 1994 65.43123890899737 1995 65.74296078575571 1996 66.1012726402643 1997 66.35424343838774 1998 66.64203160646876 1999 67.03263813996786 2000 67.32094830177742 2001 67.6854376989284 2002 68.02984873232268 2003 67.86219152676688 2004 68.26423767601469 2005 68.52895220997465 2006 68.63130711003714 2007 68.99282181263689 2008 69.43078565557563 2009 69.84310374004826 2010 70.0811272128099 2011 70.33141458762931 2012 70.1790587361453 2013 70.21633351009262 2014 70.5171079665288 2015 70.83281139958662 2016 70.96616310223037 2017 71.36827964407516 2018 71.64244587646458 2019 71.86226926535632 2020 70.81257615741481 2021 70.63979644269978 2022 71.11852277019248