Year years 1960 68.323 1961 69.064 1962 69.466 1963 69.804 1964 70.345 1965 70.98 1966 71.253 1967 71.766 1968 71.918 1969 72.428 1970 72.692 1971 72.976 1972 73.399 1973 73.755 1974 74.085 1975 73.49 1976 73.8 1977 74.13 1978 74.16 1979 74.11 1980 74.15 1981 74.15 1982 74.36 1983 74.27 1984 74.27 1985 74.83 1986 75.24 1987 75.24 1988 75.34 1989 75.64 1990 75.93 1991 75.95 1992 75.8 1993 76.04 1994 76.28 1995 76.52 1996 76.76 1997 76.9 1998 76.22 1999 76.55 2000 76.68 2001 78.17 2002 78.4 2003 78.23 2004 79.08 2005 78.83 2006 79.33 2007 79.25 2008 79.6 2009 79.6 2010 79.6 2011 79.9 2012 80.1 2013 80.2 2014 80.5 2015 80.4 2016 81.3 2017 80.9 2018 81.4 2019 81.6 2020 80.9 2021 79.6 2022 80.7