Year years 1960 39.21 1961 40.986 1962 42.656 1963 44.205 1964 45.965 1965 47.403 1966 48.824 1967 50.032 1968 51.242 1969 52.644 1970 53.756 1971 54.904 1972 56.023 1973 56.807 1974 58.132 1975 59.115 1976 60.263 1977 60.85 1978 61.517 1979 62.103 1980 62.635 1981 63.064 1982 63.417 1983 64.069 1984 64.659 1985 65.031 1986 65.645 1987 65.975 1988 66.534 1989 66.812 1990 67.372 1991 67.715 1992 68.288 1993 68.524 1994 68.705 1995 69.25 1996 69.487 1997 69.342 1998 69.189 1999 69.287 2000 68.816 2001 68.912 2002 68.962 2003 69.145 2004 69.46 2005 69.545 2006 69.658 2007 69.819 2008 70.07 2009 70.186 2010 70.182 2011 66.833 2012 69.774 2013 69.983 2014 68.237 2015 68.5 2016 68.501 2017 69.63 2018 70.017 2019 69.496 2020 69.867 2021 69.63 2022 69.736