Year years 1960 65.86053658536586 1961 65.87714634146343 1962 65.25565853658537 1963 67.07170731707318 1964 67.84512195121953 1965 67.70726829268293 1966 68.89765853658538 1967 67.51595121951219 1968 67.56036585365854 1969 66.69207317073172 1970 67.48241463414635 1971 68.50414634146341 1972 68.47024390243904 1973 69.00560975609757 1974 69.49975609756099 1975 69.6139024390244 1976 69.69878048780488 1977 69.7419512195122 1978 69.48048780487805 1979 69.15317073170733 1980 69.09097560975611 1981 69.36829268292684 1982 69.53170731707318 1983 69.72634146341466 1984 69.65878048780489 1985 69.7068292682927 1986 69.49634146341464 1987 69.22682926829269 1988 69.38804878048781 1989 69.53073170731709 1990 69.74121951219513 1991 69.78439024390244 1992 69.78439024390244 1993 69.56341463414635 1994 69.50975609756098 1995 69.4560975609756 1996 69.10487804878049 1997 69.0048780487805 1998 69.80731707317075 1999 70.51219512195124 2000 71.16341463414635 2001 71.16097560975611 2002 71.00975609756098 2003 71.30975609756098 2004 71.5609756097561 2005 71.91219512195123 2006 72.16341463414635 2007 72.56585365853658 2008 72.56585365853658 2009 73.30975609756098 2010 73.45853658536586 2011 74.40975609756099 2012 74.41219512195123 2013 75.06341463414634 2014 74.90975609756099 2015 74.91219512195123 2016 75.20975609756098 2017 75.20975609756098 2018 75.35853658536587 2019 75.60731707317073 2020 74.25365853658539 2021 72.80975609756098 2022 75.3048780487805