Year years 1960 42.67927723794427 1961 43.083039373548665 1962 43.43142034074281 1963 43.719840932642086 1964 44.3594799850617 1965 44.450467202142924 1966 44.228213717935915 1967 45.02973624315186 1968 45.37851952255648 1969 45.6806524978246 1970 45.99573079355831 1971 46.49757031589373 1972 46.29971911026424 1973 46.979038808228445 1974 46.988665205722384 1975 47.25046855198374 1976 48.043508606355104 1977 48.38222953931594 1978 48.71201470752646 1979 49.157426532421745 1980 49.56305653378242 1981 49.82690126824183 1982 50.07343573989203 1983 48.69852509397707 1984 48.752529523901245 1985 49.08323749225223 1986 50.0046061263699 1987 50.82656910023067 1988 50.37042105964324 1989 51.72793538691715 1990 51.90239645413933 1991 51.712008656102896 1992 51.63918139441642 1993 52.45974793771162 1994 52.93009875880017 1995 52.69862961228591 1996 52.83532024731193 1997 53.26926027460107 1998 53.14017430750132 1999 54.24247015778335 2000 54.81990723180813 2001 55.28445564044205 2002 55.76991471367071 2003 56.88742997928049 2004 57.36981534028053 2005 58.02714106519945 2006 58.87715846751887 2007 59.623664090111724 2008 60.22317991582877 2009 61.02901958177754 2010 61.52659277060244 2011 62.15969539322821 2012 62.545773344407195 2013 63.06374285702944 2014 63.46874282904987 2015 63.914282460027536 2016 64.49976515600281 2017 64.95669696761145 2018 65.43605685997511 2019 65.81821929517227 2020 65.36778175436187 2021 65.03923683537428 2022 65.56025784853254