Year years 1960 42.383892629137414 1961 42.74432071771633 1962 43.098002107123534 1963 43.32223905136244 1964 43.853790108522894 1965 44.01685203805457 1966 43.89304275259955 1967 44.57140896392715 1968 44.89833571571205 1969 45.182683534349934 1970 45.494036810267964 1971 45.883432926473574 1972 45.66127500705391 1973 46.33939134010709 1974 46.3592792272195 1975 46.732000463177854 1976 47.48509806388399 1977 47.876428755746275 1978 48.16033151802715 1979 48.61191544399059 1980 49.00385283797429 1981 49.32629046736276 1982 49.61087353157509 1983 48.41468113563983 1984 48.486812898893156 1985 48.79695794775239 1986 49.581328129587284 1987 50.47193901896843 1988 50.27353835454087 1989 51.10459038856759 1990 51.20231532910359 1991 51.03796127690928 1992 51.038880727658636 1993 51.58910712802778 1994 51.77247540786901 1995 52.356355506336726 1996 52.47727709212634 1997 52.805639365232416 1998 52.81849855730205 1999 53.60603194538354 2000 54.097068164575866 2001 54.533550881164096 2002 55.024094120843216 2003 55.61800591379254 2004 56.133524854907066 2005 56.85530188197141 2006 57.67825176087323 2007 58.40292894008173 2008 59.05935485540774 2009 59.87241604651599 2010 60.22501750502858 2011 61.22677376910511 2012 61.902701364619475 2013 62.58673042593933 2014 63.11675020828696 2015 63.63866727726479 2016 64.2490089798582 2017 64.64449467167111 2018 65.12106924161023 2019 65.55023100856518 2020 65.04347979538213 2021 64.67721008303958 2022 65.19967952606513