Year years 1960 64.4880574893965 1961 64.72250756608348 1962 64.56461390372795 1963 64.86235789049246 1964 65.34947163450006 1965 65.30588771696392 1966 65.43305183617363 1967 65.39153441134691 1968 65.30314928875902 1969 65.0211465003175 1970 65.43878894335354 1971 65.58584387617393 1972 65.82266299346351 1973 65.93645274910253 1974 66.09270122483701 1975 65.98912494207435 1976 66.10123475898594 1977 66.20816302078016 1978 66.26137935706582 1979 66.34171135657066 1980 66.46122938264719 1981 66.75460709088351 1982 67.0809660871852 1983 67.12545218612921 1984 67.23354636122309 1985 67.52391458956576 1986 68.20880480324934 1987 68.4222915874976 1988 68.48535649500441 1989 68.53482989874561 1990 68.45161051601445 1991 68.38260441840933 1992 68.05666817320619 1993 67.5411893940251 1994 67.58008932545124 1995 67.72751380796645 1996 68.26601004745994 1997 68.77319194256766 1998 69.13856342120877 1999 69.08011958954052 2000 69.30141129845225 2001 69.59987278984171 2002 69.74864043344931 2003 69.90169032371693 2004 70.33133763359812 2005 70.49153929560657 2006 71.05092526114942 2007 71.46132959207696 2008 71.79034493854171 2009 72.24202065404228 2010 72.58018188952236 2011 73.06235632719329 2012 73.32642364616211 2013 73.70217976894243 2014 74.01982167245299 2015 74.02992875880255 2016 74.37255345505933 2017 74.6695943862636 2018 74.80408936770381 2019 75.10282884266765 2020 73.83164026513549 2021 73.65528897079069 2022 74.7960734645677