Year years 1960 52.393067087531904 1961 52.928526219900064 1962 53.416338523842995 1963 53.878442322576554 1964 54.33305143211003 1965 54.66320909799497 1966 55.11084462249936 1967 55.450449283730336 1968 55.77957553371919 1969 56.1293787942191 1970 56.16985631167989 1971 56.96599283272233 1972 57.34758087373228 1973 57.818900014715275 1974 58.18808376434379 1975 58.635277998040934 1976 58.84688596140117 1977 59.29708830992073 1978 59.597105284060035 1979 59.90783893284404 1980 60.338842711702604 1981 60.7489327244994 1982 61.05510671264622 1983 61.67708939184955 1984 62.08588894561166 1985 62.44915994963074 1986 63.00543041000668 1987 63.398305992747154 1988 63.834663906838706 1989 64.15098263489058 1990 64.32245881445257 1991 64.64646808735155 1992 64.96683019635607 1993 65.30991433890934 1994 65.74975977819598 1995 66.03386108717163 1996 66.44142916738868 1997 66.77588209553936 1998 67.0857207450026 1999 67.52725566916303 2000 67.73291859441122 2001 68.07711863251788 2002 68.36597626709784 2003 68.69203265208583 2004 68.98688578253409 2005 69.40106524545348 2006 69.62294047862751 2007 69.7822597520309 2008 70.06393517915544 2009 70.28633723152905 2010 70.16813721276392 2011 70.6740975077774 2012 70.90314947471185 2013 71.20200321816081 2014 71.47767232924092 2015 71.47412352932385 2016 71.41440127046386 2017 71.63415636500072 2018 71.74917562197695 2019 71.91993487576703 2020 69.49765673030795 2021 68.58469608985021 2022 70.54885430784164