Year years 1960 59.552734592702144 1961 59.860676196146926 1962 60.19852132001163 1963 60.38462426828502 1964 60.898087398146174 1965 61.47357033839019 1966 61.68772155251353 1967 61.923019855674255 1968 62.19498141259683 1969 62.368401442755335 1970 62.81336937084595 1971 63.16723984386167 1972 63.504595028408964 1973 63.75588399328457 1974 63.86600543520724 1975 63.476377749969885 1976 63.95114716229213 1977 64.11953325444608 1978 64.04247997561703 1979 64.35200451470841 1980 65.44225612515882 1981 65.63427333601425 1982 65.9284795264754 1983 66.20094956986753 1984 66.76833996675884 1985 67.06610299302915 1986 67.32896947798376 1987 67.7851843615894 1988 68.11180251064918 1989 68.28185327795669 1990 68.54483872102684 1991 68.64958830562341 1992 68.68061673716946 1993 68.73368641846037 1994 68.29871696580054 1995 68.6412562589437 1996 68.80313531874367 1997 68.87919767483719 1998 68.69070035774683 1999 68.4542480233473 2000 69.43557417378726 2001 69.75335539838306 2002 69.92597158046017 2003 69.96908227575499 2004 70.29564448707549 2005 70.53389432740626 2006 70.84693376043184 2007 71.30466444555074 2008 71.6601390440902 2009 72.08812732352118 2010 72.67931406778443 2011 73.126797013982 2012 73.47226485537286 2013 73.92108895366256 2014 74.3716311428494 2015 74.68834923713626 2016 75.05513419567755 2017 75.48084401562969 2018 75.63452619738656 2019 75.86755301976325 2020 75.7238950781155 2021 74.8828022456099 2022 75.33616421763348