Year years 1960 43.325090725528696 1961 44.010206163981444 1962 44.409726325451935 1963 45.39347685150706 1964 46.36861910526487 1965 46.68458044266135 1966 46.856743273322905 1967 47.25104523309334 1968 47.83725583459118 1969 48.163572836583704 1970 48.70413647130506 1971 49.682731629910286 1972 50.26710897864041 1973 50.84830772530231 1974 51.54952787896497 1975 51.95617933735132 1976 52.377482046763916 1977 53.736279186733206 1978 54.47925943318537 1979 55.18031655180769 1980 55.41726491680924 1981 55.678317980665724 1982 55.92042701276114 1983 56.6460466787608 1984 57.34073661471009 1985 58.08393924989044 1986 58.94597886522977 1987 58.934014315196016 1988 58.24167875853867 1989 60.4168536274542 1990 60.83449477145144 1991 61.2571484976589 1992 61.59868189823465 1993 62.576984898727645 1994 63.7105519963085 1995 63.426871979956644 1996 63.83793094673802 1997 64.09031693344149 1998 63.881163515724204 1999 65.0773565638944 2000 65.42538680875262 2001 65.76819991382179 2002 66.05959811040817 2003 65.88867340943733 2004 65.83818101173354 2005 66.07524457362692 2006 66.45136397070497 2007 66.82295242311513 2008 67.30176004862759 2009 67.90172268587281 2010 68.14341185757839 2011 68.35467226009004 2012 68.19819209429055 2013 68.16905025758487 2014 68.45360404457486 2015 68.80646768348508 2016 68.86461346474466 2017 69.33365975257307 2018 69.60939620510314 2019 69.90696576423151 2020 68.9362228892435 2021 68.83243331785962 2022 69.25703176189923