Year years 1960 43.42295374721575 1961 44.11603266380349 1962 44.349759174164966 1963 45.696742897804974 1964 46.394212135790376 1965 46.98998649305563 1966 47.43446441325075 1967 47.85159711401967 1968 48.295711476463616 1969 48.85086001504421 1970 49.40004567803155 1971 50.07544210542965 1972 50.6400942045653 1973 50.991782301141114 1974 51.812356225582484 1975 52.29167928787914 1976 52.782737959676425 1977 54.09029656144516 1978 54.59836975074361 1979 55.719476541144054 1980 55.67093883640497 1981 54.927617537583146 1982 55.25621990452524 1983 56.87193410702064 1984 58.50059858363863 1985 59.27823598810598 1986 59.72285529773431 1987 60.62738114589016 1988 60.964824415181205 1989 62.36323396226743 1990 62.322406494046 1991 63.624964207158534 1992 64.25944622538825 1993 64.59486131881961 1994 64.6331286254714 1995 64.94431479781427 1996 65.30691559012496 1997 65.5678834948826 1998 65.83527741544381 1999 66.2334595910548 2000 66.51957647270861 2001 66.86584225752406 2002 67.20712976883492 2003 66.9564806344295 2004 67.37419507431996 2005 67.59414885898948 2006 67.64222381976096 2007 67.97671772072727 2008 68.39549341118244 2009 68.78902679265086 2010 68.98794239878012 2011 69.19215100043041 2012 68.95123206878907 2013 68.93763013102942 2014 69.29005166220246 2015 69.60412719784802 2016 69.71281235036517 2017 70.17581460307618 2018 70.49153340848173 2019 70.72703466980353 2020 69.73565235417047 2021 69.51306322469391 2022 69.90672126902713