Year years 1960 73.9 1961 73.7 1962 74.1 1963 74.2 1964 74.3 1965 74.3 1966 74.3 1967 74.7 1968 74.3 1969 74.7 1970 74.5 1971 75 1972 74.8 1973 75.1 1974 75.1 1975 75.6 1976 75.7 1977 75.6 1978 76.4 1979 76.5 1980 75.8 1981 76.9 1982 76.9 1983 76.9 1984 77.7 1985 76.8 1986 77.4 1987 77.2 1988 77.6 1989 78 1990 78.4 1991 78.9 1992 79.3 1993 79.2 1994 79.7 1995 79.5 1996 79.4 1997 80.1 1998 80.8 1999 80.4 2000 81.3 2001 81.1 2002 81.1 2003 81.4 2004 81.7 2005 81.9 2006 82.2 2007 82.2 2008 82.4 2009 82.7 2010 82.8 2011 83 2012 83.2 2013 83.3 2014 83.27 2015 83.4 2016 83.4 2017 83.6 2018 83.5 2019 83.9 2020 84.1 2021 84 2022 84.4