Year years 1960 61.30941629241064 1961 61.62900304852647 1962 61.78775373078418 1963 62.217720184290066 1964 62.60991866738386 1965 62.72847431543614 1966 62.90030952296123 1967 63.03895575247165 1968 63.21885843298883 1969 63.25265839237391 1970 63.39830911586943 1971 63.71228840235611 1972 63.95445963792846 1973 64.1899443210743 1974 64.38317681807963 1975 64.57068073617765 1976 64.72626041243859 1977 64.88398311332534 1978 65.05931322982757 1979 65.15119825196317 1980 65.66711406487725 1981 65.93196335150081 1982 66.22394112136007 1983 66.4321534821756 1984 66.58359535945416 1985 66.89605640897508 1986 67.58789572649457 1987 67.90450918442086 1988 67.85083912225879 1989 68.28612233038538 1990 68.29618502810794 1991 68.08189890753543 1992 67.3515443274935 1993 67.01790269011346 1994 67.32830419005538 1995 67.25558022681679 1996 67.57318110248787 1997 67.93999129817857 1998 68.39910610232441 1999 68.36502467957514 2000 68.89210391256906 2001 69.19695347566201 2002 69.50649770029291 2003 69.75475096728422 2004 70.02035093475948 2005 70.09322664473129 2006 70.40231143337712 2007 70.70877557729222 2008 71.0024390027901 2009 71.48283562474815 2010 71.87842997045729 2011 72.0742519929248 2012 72.53715881244561 2013 72.94263408785908 2014 73.17490419263967 2015 73.34784353464016 2016 73.56011775463492 2017 73.90620692008899 2018 74.10373587660713 2019 74.33142483756792 2020 72.6714543269783 2021 72.59312502106471 2022 74.10651393979416