Year years 1960 50.89433055076839 1961 52.846477494913074 1962 55.20878268737837 1963 55.54242961306407 1964 56.03495286225328 1965 55.860706313139815 1966 56.38980370426508 1967 56.79483280739327 1968 57.22546217024157 1969 57.535588899067584 1970 57.84098146951919 1971 57.967285963965836 1972 58.79295675912965 1973 59.29467367233107 1974 59.71366648291249 1975 60.16614914652639 1976 60.62583826479465 1977 61.120966079007225 1978 61.48148995615571 1979 61.90281717177587 1980 62.23361693996492 1981 62.61140176530314 1982 62.97232218864961 1983 63.2157593749811 1984 63.52021651796131 1985 63.81240262255821 1986 64.20835065275762 1987 64.51289390839285 1988 64.68498122844785 1989 65.02292628822602 1990 65.1885074558445 1991 65.33529375864678 1992 65.59648551324398 1993 65.78035307613769 1994 66.02536951644852 1995 66.2157756641036 1996 66.4801590543829 1997 66.82185012918286 1998 67.09683991065145 1999 67.38722653654123 2000 67.70052424109822 2001 68.05237150572788 2002 68.33338793034197 2003 68.6069221384269 2004 68.86237766296075 2005 69.19881209874619 2006 69.57129841886548 2007 69.83519377507928 2008 70.00607203893297 2009 70.4014786893824 2010 70.67112932660098 2011 71.00821736096977 2012 71.28424956061107 2013 71.57710090377107 2014 71.880681611011 2015 72.09417499926323 2016 72.34420066844628 2017 72.54135838501652 2018 72.78303635329232 2019 72.97902041767821 2020 72.24250459906702 2021 71.32715673746287 2022 71.99635238358407