Year years 1960 70.6 1961 70.8 1962 70.5 1963 71.5 1964 71.6 1965 72.4 1966 72.9 1967 72.6 1968 73.6 1969 73.1 1970 73.3 1971 73.3 1972 74.2 1973 74.3 1974 74.6 1975 74.3 1976 74.6 1977 74.5 1978 74.5 1979 74.9 1980 74.4 1981 75.2 1982 75.2 1983 75.2 1984 75 1985 74.8 1986 75.1 1987 75.2 1988 75.67 1989 75.5 1990 75.5 1991 75.3 1992 75.7 1993 76 1994 76.1 1995 76.4 1996 76.6 1997 77 1998 77.3 1999 77.5 2000 78 2001 78.4 2002 78.8 2003 78.9 2004 79.2 2005 79.4 2006 79.6 2007 79.7 2008 80 2009 80.1 2010 80.6 2011 81.1 2012 81.1 2013 81.2 2014 81.7 2015 81.6 2016 82 2017 81.8 2018 81.7 2019 81.9 2020 80.7 2021 79.6 2022 81.3