Year years 1960 45.70738061146006 1961 46.11873744762684 1962 46.47932549522507 1963 46.77237014297199 1964 47.350161565708454 1965 47.42047396615191 1966 47.118291326879806 1967 47.84522502014856 1968 48.151971796256554 1969 48.3988985188352 1970 48.68132697267159 1971 49.206512088718256 1972 48.91536422280059 1973 49.59700211574279 1974 49.48796891505771 1975 49.61900931046598 1976 50.33142633447783 1977 50.6851958046723 1978 50.92937190930306 1979 51.36497203864533 1980 51.71798435040509 1981 52.221953771655194 1982 52.493403158805975 1983 50.89751396361993 1984 51.01596675522178 1985 51.34797651376731 1986 52.00564100962657 1987 52.59736337317971 1988 51.98749759301027 1989 53.08071897969951 1990 53.065839551473395 1991 52.74605512710586 1992 52.367848448540926 1993 52.73532522381451 1994 53.032132237113814 1995 53.189836775986535 1996 52.96035916512349 1997 53.038581734363135 1998 52.620748145347015 1999 53.39611393051324 2000 53.66220754896184 2001 53.77262631187071 2002 54.104872027507035 2003 54.49536529610089 2004 55.02003709095081 2005 55.71769736300472 2006 56.671295284548506 2007 57.531256546039806 2008 58.379386485734216 2009 59.450952771932904 2010 60.309674621723175 2011 61.3002881377364 2012 62.14798379484718 2013 62.93590022030261 2014 63.64117730706809 2015 64.19112513460563 2016 64.86779082283422 2017 65.30400970153788 2018 65.8281070906573 2019 66.21972630008455 2020 65.8364652190824 2021 65.07847216073229 2022 65.49063791294859