Year years 1960 56.52992633642667 1961 56.93055052174418 1962 57.29761385120915 1963 57.345736606499706 1964 57.93832909260761 1965 58.616172835156824 1966 58.85369129574031 1967 59.06544063991824 1968 59.32168867125045 1969 59.47019053350606 1970 59.87599129864934 1971 60.1953877050665 1972 60.528581113791745 1973 60.872251010155125 1974 59.64922060974202 1975 60.1368889593555 1976 60.5385821159549 1977 60.77163175835919 1978 60.73075719744059 1979 61.05430509161543 1980 61.92625103963017 1981 62.26502444337462 1982 62.56185937748237 1983 62.81959390773363 1984 63.37012158059438 1985 63.68644531795363 1986 64.05820416049237 1987 64.56817580353265 1988 64.83294648103147 1989 65.5541010642658 1990 65.62670770191248 1991 65.65101489636324 1992 65.64647152447779 1993 65.75668898464917 1994 65.43893977990558 1995 65.60659103417622 1996 65.92224877607697 1997 65.93382052245423 1998 65.80436603860456 1999 65.59302447657097 2000 66.8671665418733 2001 67.13489773175188 2002 67.29447564831041 2003 67.50214427799926 2004 67.78494106794116 2005 68.1048848286788 2006 68.42370250474332 2007 68.84462039765137 2008 69.28225147362626 2009 69.75630917767893 2010 70.31829303821455 2011 70.71672987045707 2012 71.12869333897062 2013 71.58339159079861 2014 71.93342679560894 2015 72.29156326693881 2016 72.62721997104532 2017 73.0133546433457 2018 73.24014831215477 2019 73.4700633121699 2020 73.17339643956473 2021 72.36689870100471 2022 72.87026255598097