Year years 1960 66.46 1961 67.054 1962 67.539 1963 67.997 1964 68.412 1965 68.816 1966 69.226 1967 69.625 1968 70.108 1969 70.52 1970 70.903 1971 71.294 1972 71.859 1973 72.407 1974 72.881 1975 73.326 1976 73.786 1977 74.256 1978 74.686 1979 75.08 1980 75.471 1981 75.915 1982 76.371 1983 76.767 1984 77.15 1985 77.561 1986 77.942 1987 78.39 1988 78.643 1989 79.1 1990 79.468 1991 80.052 1992 80.51 1993 80.93 1994 81.361 1995 81.799 1996 82.642 1997 82.769 1998 83.177 1999 83.571 2000 83.49 2001 83.955 2002 84.138 2003 84.299 2004 84.498 2005 84.739 2006 85.163 2007 85.496 2008 85.83 2009 86.098 2010 86.164 2011 86.292 2012 86.341 2013 86.831 2014 86.773 2015 86.784 2016 87.018 2017 87.094 2018 87.439 2019 87.573 2020 87.771 2021 87.948 2022 87.98