Year years 1960 53.718132228866125 1961 54.20729392857625 1962 54.59943588206694 1963 54.53505181772352 1964 55.19509074514987 1965 55.963434549110865 1966 56.22191801236695 1967 56.41864001431598 1968 56.66514637750816 1969 56.79441923592754 1970 57.16017787008232 1971 57.44855706326682 1972 57.78214934359062 1973 58.20858293656207 1974 56.19643529573603 1975 57.19756015095588 1976 57.54307754245129 1977 57.82507613633827 1978 57.80408374481673 1979 58.148277221250744 1980 58.8814667368853 1981 59.3572314783794 1982 59.66495187585558 1983 59.90546421734789 1984 60.44789013253111 1985 60.769899647988936 1986 61.2365222731759 1987 61.791027130652125 1988 61.98550701989377 1989 63.042326601801946 1990 62.947222313421044 1991 62.901698159822324 1992 62.879985256197145 1993 63.04226167149118 1994 62.84179965397136 1995 62.85072757699456 1996 63.29464685385468 1997 63.250326655862864 1998 63.17934329896567 1999 63.000184543017475 2000 64.52166616685008 2001 64.7491581194235 2002 64.90178127362402 2003 65.255287529458 2004 65.51106856779259 2005 65.90773222518393 2006 66.24221879658592 2007 66.63924452612633 2008 67.14993494819458 2009 67.6711698788984 2010 68.21228702475155 2011 68.56631708241152 2012 69.03218390676588 2013 69.49018751036354 2014 69.75927312623169 2015 70.15889608006857 2016 70.46543744102539 2017 70.81945640853107 2018 71.10901866390812 2019 71.33222194168023 2020 70.91928632978205 2021 70.1609581117454 2022 70.6968186579834