Year years 1960 67.933 1961 68.519 1962 69.083 1963 66.875 1964 67.364 1965 70.425 1966 70.768 1967 71.285 1968 71.428 1969 71.663 1970 72.084 1971 72.405 1972 73.014 1973 73.168 1974 71.681 1975 73.356 1976 73.742 1977 74.049 1978 74.4 1979 74.422 1980 74.494 1981 74.407 1982 74.496 1983 74.503 1984 74.431 1985 74.862 1986 74.572 1987 75.196 1988 75.273 1989 75.566 1990 75.382 1991 75.478 1992 76.139 1993 76.722 1994 76.526 1995 77.158 1996 77.567 1997 77.958 1998 78.417 1999 78.363 2000 78.552 2001 79.02 2002 79.635 2003 79.992 2004 80.105 2005 80.287 2006 80.522 2007 81.006 2008 81.198 2009 81.766 2010 82.048 2011 82.336 2012 82.15 2013 82.405 2014 82.723 2015 82.873 2016 83.185 2017 83.415 2018 83.058 2019 83.27 2020 83.448 2021 83.204 2022 83.673