Year years 1960 67.783 1961 68.269 1962 68.579 1963 68.992 1964 69.18 1965 69.449 1966 69.901 1967 70.281 1968 70.673 1969 71.135 1970 71.585 1971 72.006 1972 72.785 1973 73.487 1974 73.909 1975 74.284 1976 74.417 1977 74.525 1978 74.615 1979 74.746 1980 74.83 1981 75.298 1982 75.504 1983 75.707 1984 75.855 1985 76.052 1986 76.139 1987 76.117 1988 76.113 1989 76.147 1990 76.196 1991 76.147 1992 76.181 1993 76.218 1994 76.253 1995 76.36 1996 76.403 1997 76.355 1998 76.378 1999 76.466 2000 76.477 2001 76.495 2002 76.555 2003 76.503 2004 76.45 2005 76.56 2006 76.542 2007 76.478 2008 76.944 2009 77.371 2010 78.612 2011 78.62 2012 78.603 2013 78.803 2014 78.614 2015 78.644 2016 78.486 2017 78.794 2018 78.854 2019 79.01 2020 78.445 2021 77.315 2022 77.681