Year years 1960 71.51 1961 72.214 1962 71.5 1963 71.749 1964 73.08 1965 72.536 1966 72.614 1967 72.782 1968 72.773 1969 73.042 1970 73.259 1971 72.881 1972 73.93 1973 74.362 1974 73.846 1975 73.843 1976 73.707 1977 75.358 1978 75.305 1979 76.141 1980 75.407 1981 75.971 1982 76.395 1983 76.43 1984 76.656 1985 77.159 1986 77.817 1987 77.432 1988 78.664 1989 77.894 1990 78.617 1991 79.1 1992 79.1 1993 79.4 1994 79.7 1995 80.2 1996 79.9 1997 79.8 1998 80.5 1999 81.1 2000 81.1 2001 81 2002 81.5 2003 80.8 2004 82.4 2005 82.3 2006 81.9 2007 82.2 2008 83.1 2009 83.3 2010 83.5 2011 83.6 2012 83.8 2013 83.9 2014 85.2 2015 84.7 2016 85.4 2017 84.4 2018 84.6 2019 85.2 2020 84.5 2021 84.8 2022 85.3