Year years 1960 56.77763523368401 1961 57.33976405723329 1962 57.81116910906313 1963 58.270985207297294 1964 58.78052779905549 1965 59.2229271860171 1966 59.620951668824596 1967 60.01291754563385 1968 60.40930625648281 1969 60.790421563192254 1970 60.75564062262292 1971 61.68755958910727 1972 62.11269392190574 1973 62.67728693035854 1974 63.10326121063982 1975 63.685207665395595 1976 63.98730502644425 1977 64.64720097561714 1978 65.08615162028701 1979 65.52276220403182 1980 65.96439061643946 1981 66.51506898058703 1982 66.87060225234673 1983 67.4120810737117 1984 67.85059295805938 1985 68.1125496177949 1986 68.76604486181355 1987 69.25330892020573 1988 69.69743441095947 1989 70.14010054886452 1990 70.57461419506241 1991 70.92664352015655 1992 71.29721323354813 1993 71.64554570598891 1994 72.0048254405634 1995 72.37171525506116 1996 72.7626892799803 1997 73.10945944672585 1998 73.33543107488681 1999 73.80083317651916 2000 74.22162671564777 2001 74.57099064629985 2002 74.84332799089297 2003 74.98283627498422 2004 75.30852339989332 2005 75.63925424261801 2006 75.85734187556072 2007 75.99298662895534 2008 76.21293373494429 2009 76.39140845766654 2010 76.25399130559552 2011 76.77010554251224 2012 77.02986912986859 2013 77.22798827760217 2014 77.41698207085437 2015 77.51883641368644 2016 77.58952191522944 2017 77.69343870494829 2018 77.83769115285286 2019 78.04876167156688 2020 76.36433713798937 2021 75.43874180582448 2022 76.7420485862062