Year years 1960 56.86582643799203 1961 57.22146159839703 1962 58.1342936549721 1963 58.592297358801474 1964 59.26459622933096 1965 59.53173504191125 1966 59.79518776369776 1967 60.12350389145812 1968 60.46214559007153 1969 60.65787101681079 1970 60.84416552663237 1971 61.00532750837656 1972 61.16074966022003 1973 61.3001037991752 1974 61.61682759592017 1975 61.86015307327201 1976 62.05415519690439 1977 62.19384297790068 1978 62.402052912106825 1979 62.60193987336707 1980 62.85111828804849 1981 63.15070366043374 1982 63.40796153543851 1983 63.36229000158927 1984 63.78460234338897 1985 63.874109668428304 1986 63.789945301497205 1987 63.906236151201114 1988 64.09350637091926 1989 64.29747080137321 1990 64.5063164230482 1991 64.53309756091429 1992 64.75848249722202 1993 65.0330625788145 1994 65.16364100741674 1995 65.06977793507905 1996 65.0647638446448 1997 65.15997034924992 1998 65.32226013823374 1999 65.50154406382124 2000 65.67538760001894 2001 65.77476970305999 2002 65.87948727645241 2003 65.91963204266499 2004 66.26759586265163 2005 66.57870465229443 2006 66.96354373269642 2007 67.37038637028455 2008 67.63029040262387 2009 67.90417098695599 2010 68.07142325199153 2011 68.2095422926216 2012 68.38835238233324 2013 68.48989940696147 2014 68.64830990191403 2015 68.86864745578134 2016 69.17791016743298 2017 69.37363143561375 2018 69.58662711947638 2019 69.37371913479504 2020 69.14898637094947 2021 67.40863839826704 2022 67.92645987150296