Year years 1960 44.270444767753446 1961 47.031306177140166 1962 50.60570000882726 1963 51.08093182602807 1964 51.59878484740039 1965 51.16811058081194 1966 51.93733650609196 1967 52.42967933269241 1968 53.130321939294994 1969 53.54343109477885 1970 54.08081766052286 1971 54.731513872571206 1972 55.180434084639806 1973 55.83490521653899 1974 56.34109341195644 1975 56.91492426123719 1976 57.444636262556784 1977 57.93027613718612 1978 58.35773707902105 1979 58.813643379374405 1980 59.178146674268994 1981 59.56233109410564 1982 59.995353979683586 1983 60.421410120196796 1984 60.8448455727753 1985 61.27544951075822 1986 61.758725050647804 1987 62.104040367654086 1988 62.370601637071495 1989 62.713385867001875 1990 62.90316239094936 1991 63.26041934264819 1992 63.54320553518978 1993 63.729164261323916 1994 64.01944591473577 1995 64.35443148464498 1996 64.72224436114745 1997 65.11527255430897 1998 65.44797175942124 1999 65.6922358052948 2000 65.97375542732398 2001 66.28163217976005 2002 66.62132797090204 2003 66.86867589633395 2004 67.10520614177362 2005 67.4954860460598 2006 67.82774920007715 2007 68.09761892470972 2008 68.32250158618447 2009 68.68195425842993 2010 68.96516099454462 2011 69.30591251248592 2012 69.6495556842752 2013 70.0193766368167 2014 70.40763018925671 2015 70.73365439809416 2016 70.97763612155754 2017 71.16594079846824 2018 71.48426725244273 2019 71.68059235384804 2020 70.82680118581823 2021 69.63185662027102 2022 70.4650746326166