Year years 1960 64.242 1961 64.303 1962 63.602 1963 65.4 1964 66.09 1965 65.978 1966 67.004 1967 65.514 1968 65.515 1969 64.495 1970 65.219 1971 66.27 1972 66.28 1973 66.83 1974 67.29 1975 67.37 1976 67.45 1977 67.42 1978 67.1 1979 66.68 1980 66.53 1981 66.7 1982 66.8 1983 66.98 1984 66.81 1985 66.78 1986 66.55 1987 66.3 1988 66.51 1989 66.56 1990 66.59 1991 66.56 1992 66.56 1993 66.1 1994 65.9 1995 65.7 1996 65.3 1997 65.2 1998 66.1 1999 67 2000 67.7 2001 67.6 2002 67.4 2003 67.7 2004 68 2005 68.4 2006 68.7 2007 69.2 2008 69.2 2009 69.7 2010 69.8 2011 70.8 2012 70.9 2013 71.6 2014 71.3 2015 71.4 2016 71.6 2017 71.6 2018 71.7 2019 71.9 2020 70.4 2021 69.2 2022 71.5