Year years 1960 45.32237092412279 1961 47.75198424480284 1962 50.895592755926586 1963 51.33925806941083 1964 51.882104358188 1965 51.66966773579028 1966 52.32107054063957 1967 52.795062666591924 1968 53.45605276924298 1969 53.850361210881566 1970 54.207542864010996 1971 54.31697784563955 1972 55.354252806526624 1973 55.98904137251252 1974 56.45884931103066 1975 56.977921174782395 1976 57.51970497456922 1977 58.07001917547112 1978 58.515181077381364 1979 58.9861257653212 1980 59.418556884108504 1981 59.837938328634564 1982 60.239979420173256 1983 60.550705099474484 1984 60.887805376902215 1985 61.25565781499784 1986 61.7200654139376 1987 62.0608360982406 1988 62.280036368454375 1989 62.66616619235562 1990 62.86162672606406 1991 63.02093521574343 1992 63.30253812946258 1993 63.53058435223464 1994 63.793633903582545 1995 64.08096464208064 1996 64.34262069313364 1997 64.70856081425545 1998 65.02395839260767 1999 65.3663640105662 2000 65.70521492206643 2001 66.0855327295897 2002 66.40813923539177 2003 66.68929468947516 2004 66.92568714520947 2005 67.32225460923436 2006 67.71744148478274 2007 67.99619093192038 2008 68.17977979836434 2009 68.60358003237982 2010 68.90068032557355 2011 69.26983781107349 2012 69.58601330976376 2013 69.9111983022149 2014 70.23668228328329 2015 70.52367906168509 2016 70.80521339643148 2017 71.04228778116092 2018 71.32139442455141 2019 71.52543836924971 2020 70.82171877124978 2021 69.7899671680861 2022 70.511910539194