Year years 1960 46.95408162197766 1961 49.452534848442674 1962 52.675465090480294 1963 53.11865896154266 1964 53.664172898424745 1965 53.58676666085423 1966 54.14661415277327 1967 54.636422347761744 1968 55.299027028893825 1969 55.68613316255365 1970 56.03652721675914 1971 56.360136962262395 1972 57.17614346852325 1973 57.81134559029744 1974 58.32412529051116 1975 58.853631864396164 1976 59.40660919352458 1977 60.03833483821823 1978 60.55153752711546 1979 61.06841710799515 1980 61.55577148567471 1981 62.04256183456346 1982 62.480093823065495 1983 62.80442156772398 1984 63.14128955578796 1985 63.47968867540513 1986 63.9413587315944 1987 64.30141093755941 1988 64.5601844206917 1989 64.9223788226955 1990 65.13761572928415 1991 65.20749149018836 1992 65.50813126317391 1993 65.78886646156073 1994 66.01170976892023 1995 66.3102166017087 1996 66.52415201543349 1997 66.88682848166275 1998 67.24561623441527 1999 67.5379329808496 2000 67.90273167724604 2001 68.37646311280673 2002 68.69968620696193 2003 69.00928136897464 2004 69.24842497566479 2005 69.6858871568791 2006 70.10979297265132 2007 70.42007101984436 2008 70.58860745030756 2009 71.04103948131788 2010 71.33622969170314 2011 71.71785452606424 2012 72.06063255204671 2013 72.39954833607604 2014 72.68341380684946 2015 72.94895427453552 2016 73.2476591290598 2017 73.52646993827352 2018 73.76907850926581 2019 73.97677570810482 2020 73.395063340744 2021 72.34850800947838 2022 73.01571535276585