Year years 1960 41.6942809155079 1961 42.14361564070912 1962 42.67156852993367 1963 42.817829623419186 1964 43.47269232977721 1965 43.505792404260816 1966 43.908290743973275 1967 44.42628970028778 1968 44.79705596926499 1969 45.04350231023098 1970 44.03778239494279 1971 40.0817777256322 1972 45.547577327819035 1973 46.10178599299499 1974 46.16840489267247 1975 46.314370460828364 1976 46.93655519514606 1977 47.505560619704596 1978 47.77097709171169 1979 48.18444966316174 1980 48.69044519789367 1981 48.966412491574324 1982 49.10427687437624 1983 48.66797618451697 1984 48.63005696704102 1985 48.96339769364981 1986 49.57391758571878 1987 50.08527730758635 1988 49.98249100356814 1989 50.97871943924979 1990 51.29931477060325 1991 51.03914576800981 1992 51.518276569154345 1993 52.003871771649656 1994 52.66720063388054 1995 53.02275987840685 1996 53.215411153464544 1997 53.734293813833496 1998 53.836288433336975 1999 55.1128291734651 2000 55.675533349576796 2001 56.10244774223147 2002 56.45902004383902 2003 56.90306833347801 2004 57.262270916675504 2005 57.7839355368618 2006 58.31846030931109 2007 58.67255024308193 2008 58.82415399436294 2009 59.562405957508616 2010 60.04743424576381 2011 60.60610138729219 2012 60.83018937475067 2013 61.00836392356532 2014 61.427968483193425 2015 61.78254210759301 2016 62.251717627297445 2017 62.63612064157001 2018 63.03385328250767 2019 63.33425393914479 2020 62.832792543095465 2021 62.41706768556092 2022 63.008320058600546