Year years 1960 45.93245360612968 1961 46.66480759417704 1962 46.99663276922007 1963 47.92410657724617 1964 48.559960648958466 1965 49.16958412642579 1966 49.75356780795171 1967 50.28723776713338 1968 50.68252557703438 1969 51.33990839041214 1970 51.93123095900361 1971 52.582163332112 1972 53.14512343011851 1973 53.96253454702556 1974 54.75795418653237 1975 55.521620334992804 1976 55.91370263661964 1977 57.173957821312996 1978 57.74075333732436 1979 59.08360167259814 1980 59.92114474010615 1981 60.57391277993667 1982 61.25740577033841 1983 62.76399560969955 1984 63.64532948090524 1985 64.45405746725886 1986 65.17337982245748 1987 65.64419843526049 1988 66.08482659429181 1989 66.41956840726077 1990 66.45777767940602 1991 67.59119801917562 1992 68.09251765752876 1993 68.37967080265227 1994 68.70589453130474 1995 69.02851669328147 1996 69.45836777989665 1997 69.75147303762807 1998 69.91686269499517 1999 70.39080762765784 2000 70.83804569186275 2001 71.16652090820821 2002 71.50957929764193 2003 71.41785211304281 2004 71.97760660076875 2005 72.32071421860132 2006 72.68533502512868 2007 73.01862022672003 2008 73.0714161449755 2009 73.33706325861858 2010 73.65710784194384 2011 73.94876909319184 2012 73.91568536458213 2013 73.99059855266866 2014 74.2462646571557 2015 74.46201660946298 2016 74.91614310308161 2017 75.4877692385437 2018 75.59141583206514 2019 75.64759842941321 2020 74.73285861371376 2021 74.42502293939584 2022 74.8163689566139