Year years 1960 50.33 1961 52.112 1962 53.697 1963 55.285 1964 56.778 1965 58.228 1966 59.656 1967 61.002 1968 62.31 1969 63.475 1970 64.45 1971 65.607 1972 66.373 1973 67.183 1974 67.864 1975 68.466 1976 69.118 1977 69.604 1978 69.978 1979 70.456 1980 70.826 1981 71.183 1982 71.47 1983 71.668 1984 72.012 1985 72.106 1986 72.269 1987 72.369 1988 72.444 1989 72.619 1990 72.668 1991 72.764 1992 72.953 1993 73.375 1994 73.517 1995 73.799 1996 74.355 1997 74.535 1998 74.641 1999 74.98 2000 75.496 2001 75.908 2002 76.088 2003 76.337 2004 76.56 2005 76.931 2006 77.156 2007 77.634 2008 78.084 2009 78.461 2010 78.748 2011 78.89 2012 79.081 2013 79.246 2014 79.328 2015 79.405 2016 79.557 2017 79.689 2018 79.857 2019 80.019 2020 79.174 2021 78.76 2022 79.246