Year years 1960 41.37158810767465 1961 41.73124288706164 1962 42.06327671654 1963 42.4400532537839 1964 42.898397305561744 1965 43.078888328160055 1966 43.27159167879342 1967 43.47382456851142 1968 43.984972582134084 1969 44.28799099725185 1970 44.70600738042173 1971 45.31182824076929 1972 45.621927628420885 1973 46.37677935425741 1974 46.863859856647416 1975 47.295649633287596 1976 47.885194939388995 1977 48.49798300630587 1978 48.86983126006621 1979 49.22510507256952 1980 49.5719337187053 1981 49.95652389042633 1982 50.16721379551044 1983 49.99485697380333 1984 49.92468637676078 1985 50.061478120902116 1986 50.538499361729485 1987 50.26297624777631 1988 49.85931591337474 1989 50.70559171594411 1990 50.8008910691647 1991 50.59270313718713 1992 50.52998788858175 1993 51.034001465840205 1994 51.69375352133886 1995 51.5343398450386 1996 51.56116474881394 1997 51.74414834707896 1998 51.51728198735567 1999 52.51798046819626 2000 53.01685535133726 2001 53.43203366038699 2002 53.83787831902252 2003 54.373973294442244 2004 54.8306359382256 2005 55.4315172795202 2006 56.08831811309352 2007 56.596086862400476 2008 57.037616778517524 2009 57.71075385723165 2010 58.24331613365942 2011 58.855554967275026 2012 59.364851584493934 2013 59.897372980771976 2014 60.365895716251615 2015 60.72792996866208 2016 61.162845242451986 2017 61.651929637450856 2018 62.03515704439602 2019 62.4316538057646 2020 62.048541178069875 2021 61.734065726693444 2022 62.3412257098832