Year years 1960 65.94 1961 66.374 1962 66.843 1963 66.63 1964 67.767 1965 68.205 1966 68.619 1967 69.025 1968 69.429 1969 69.849 1970 70.295 1971 70.798 1972 71.328 1973 71.884 1974 72.448 1975 72.998 1976 73.505 1977 73.942 1978 74.303 1979 74.586 1980 74.929 1981 75.106 1982 75.259 1983 75.429 1984 75.55 1985 75.672 1986 75.799 1987 75.927 1988 76.058 1989 76.179 1990 76.297 1991 76.408 1992 76.531 1993 76.672 1994 76.851 1995 77.08 1996 77.361 1997 77.671 1998 78.003 1999 78.315 2000 78.595 2001 78.831 2002 79.022 2003 79.183 2004 79.321 2005 79.453 2006 79.578 2007 79.694 2008 79.798 2009 79.898 2010 79.99 2011 80.063 2012 80.122 2013 80.157 2014 80.166 2015 80.148 2016 80.111 2017 80.071 2018 80.051 2019 80.075 2020 80.225 2021 76.359 2022 80.565