Year years 1960 58.370512195121954 1961 58.50307317073171 1962 58.62175609756098 1963 58.94451219512196 1964 59.15748780487806 1965 59.461682926829276 1966 59.69921951219512 1967 59.87341463414635 1968 59.99836585365854 1969 60.19117073170732 1970 60.4229756097561 1971 60.647560975609764 1972 60.994951219512195 1973 61.277390243902445 1974 61.52497560975611 1975 61.790609756097574 1976 61.64034146341464 1977 61.85300000000001 1978 62.06560975609757 1979 62.25458536585367 1980 66.62439024390245 1981 66.70609756097562 1982 66.7878048780488 1983 67.66219512195123 1984 68.53658536585367 1985 68.5365853658537 1986 68.9134146341463 1987 69.290243902439 1988 68.8487804878049 1989 68.290243902439 1990 68.3365853658537 1991 67.6 1992 67.4 1993 65.4 1994 64.9 1995 63.5 1996 63.6 1997 64 1998 64.5 1999 65.63 2000 65.45 2001 65.76 2002 65.95 2003 65.74 2004 66.06 2005 65.86 2006 66.15 2007 66.34 2008 67.11 2009 68.39 2010 68.45 2011 68.69 2012 69.52 2013 70.62 2014 71.44 2015 71.97 2016 72.41 2017 72.95 2018 73.15 2019 73.18 2020 71.37 2021 70.23 2022 74.44