Year years 1960 65.939 1961 66.514 1962 66.055 1963 66.461 1964 67.209 1965 67.097 1966 67.306 1967 67.301 1968 67.304 1969 67.139 1970 66.964 1971 67.54 1972 67.162 1973 67.427 1974 67.082 1975 66.461 1976 66.47 1977 66.17 1978 66.031 1979 65.479 1980 65.756 1981 65.588 1982 65.573 1983 65.309 1984 64.811 1985 66.7 1986 67.33 1987 66.6 1988 67 1989 66.8 1990 66.3 1991 65.5 1992 64.9 1993 63.8 1994 63.5 1995 62.9 1996 63 1997 62.9 1998 62.7 1999 62.2 2000 63.4 2001 62.8 2002 62.3 2003 62.7 2004 63.2 2005 62.9 2006 63.6 2007 64.5 2008 64.7 2009 64.7 2010 64.6 2011 64.7 2012 66.6 2013 67.3 2014 67.8 2015 68.6 2016 68.9 2017 69.3 2018 69.2 2019 69.3 2020 67.306 2021 67.298 2022 68.09