Year years 1960 66.6 1961 66.8 1962 66.9 1963 67.1 1964 67.2 1965 67.3 1966 67.4 1967 67.6 1968 67.7 1969 67.8 1970 68 1971 68.2 1972 68.4 1973 68.6 1974 68.8 1975 69 1976 69.2 1977 69.4 1978 69.7 1979 69.9 1980 70.1 1981 70.3 1982 70.5 1983 70.8 1984 71 1985 71.3 1986 71.6 1987 71.8 1988 72.1 1989 72.3 1990 72.6 1991 72.8 1992 73.1 1993 73.3 1994 73.6 1995 73.8 1996 74.1 1997 74.5 1998 74.8 1999 75 2000 75.3 2001 75.5 2002 75.7 2003 75.7 2004 76.7 2005 76.7 2006 77.3 2007 77.6 2008 77.8 2009 78 2010 78.2 2011 78.7 2012 78.7 2013 79 2014 79.5 2015 79.2 2016 79.5 2017 79.6 2018 79.7 2019 79.9 2020 79.2 2021 79.3 2022 79.4