Year years 1960 63.394 1961 63.489 1962 63.161 1963 63.624 1964 64.254 1965 63.618 1966 63.449 1967 63.086 1968 62.784 1969 62.068 1970 63.08 1971 63.24 1972 63.25 1973 63.28 1974 63.13 1975 62.48 1976 62.19 1977 61.83 1978 61.83 1979 61.49 1980 61.39 1981 61.62 1982 62.25 1983 62.16 1984 61.71 1985 62.73 1986 64.78 1987 64.84 1988 64.64 1989 64.24 1990 63.73 1991 63.45 1992 62 1993 58.97 1994 57.55 1995 58.12 1996 59.62 1997 60.85 1998 61.22 1999 59.87 2000 59.03 2001 58.92 2002 58.68 2003 58.53 2004 58.91 2005 58.92 2006 60.43 2007 61.46 2008 61.92 2009 62.87 2010 63.09 2011 64.04 2012 64.56 2013 65.13 2014 65.29 2015 65.92 2016 66.5 2017 67.51 2018 67.75 2019 68.24 2020 66.49 2021 65.51 2022 67.57