Year years 1960 65.42391849653913 1961 65.77770498868381 1962 65.65192195049923 1963 65.85471921399176 1964 66.30559235586037 1965 66.31692861782187 1966 66.4805410198057 1967 66.63559220726773 1968 66.38817355065908 1969 66.41326727348554 1970 66.8133363441343 1971 67.07207688649414 1972 67.26453384954364 1973 67.4228174829903 1974 67.74584971112122 1975 67.89972510160825 1976 68.0985982551557 1977 68.35999361684244 1978 68.47608756682743 1979 68.70810662545996 1980 68.75731980610898 1981 69.12383823259637 1982 69.4876495229797 1983 69.57016618758027 1984 69.75282638778071 1985 69.9779384200225 1986 70.46515834341659 1987 70.70795337862357 1988 70.7862259211089 1989 70.9212887475697 1990 70.94799678056715 1991 71.08539167134384 1992 71.1551823530261 1993 70.9012341133466 1994 70.97979402191118 1995 71.14089212523547 1996 71.70919283680973 1997 72.18525658890462 1998 72.44716311192072 1999 72.48153668109468 2000 72.73622989052208 2001 73.03811729165878 2002 73.19919859367185 2003 73.33666631504232 2004 73.78209644971183 2005 73.92687615705073 2006 74.40324939235353 2007 74.75813871516499 2008 75.00103059150102 2009 75.39709225555326 2010 75.6198660908868 2011 75.98276322141126 2012 76.19396010365253 2013 76.45299057299961 2014 76.70903511205822 2015 76.70394071528516 2016 76.89862797063653 2017 77.07284828880712 2018 77.18055665876828 2019 77.4255063349062 2020 76.31902945671027 2021 76.01477403772512 2022 76.78032250257684