Year years 1960 44.42821383791167 1961 44.74394020573234 1962 45.118164640282245 1963 45.43169660075328 1964 45.837887652133304 1965 44.96178537889861 1966 45.561389015810626 1967 45.998553852930065 1968 47.49217851808917 1969 47.902162010350885 1970 47.62234995854185 1971 46.945338443384756 1972 49.01131409108227 1973 49.47292252447002 1974 49.986990514497016 1975 50.66026331011052 1976 51.258765502639086 1977 51.889258272326906 1978 52.53662030818085 1979 53.20198487683205 1980 53.89142369790693 1981 54.57210729620151 1982 55.197929983572635 1983 55.83345840388473 1984 56.40018827040092 1985 56.87073223955382 1986 57.39268999773379 1987 57.8616617675696 1988 58.399174438873175 1989 58.80857761520612 1990 59.35401348107284 1991 59.537268071583725 1992 60.16345958532725 1993 60.421510534592386 1994 60.817355605828475 1995 61.152424995917144 1996 61.49395444499786 1997 62.12052882948353 1998 62.778021035238616 1999 63.4571718400296 2000 63.883589197416676 2001 64.38300858428924 2002 64.93722477333218 2003 65.47071515150226 2004 65.90128225645667 2005 66.38425910013154 2006 66.97098728542812 2007 67.32334961135003 2008 67.7593940127856 2009 68.06750795106164 2010 68.6037860135185 2011 68.9987556593466 2012 69.51099570426544 2013 70.01083774702951 2014 70.40086750581276 2015 70.82718151874538 2016 71.25024937315733 2017 71.64467020647588 2018 71.91581675024953 2019 72.20045891048085 2020 71.61330381964592 2021 69.43207064892441 2022 70.0557324026669