Year years 1960 46.06561611742701 1961 46.459183188005944 1962 46.85024263293907 1963 47.162445799520555 1964 47.611692201963116 1965 47.14477374609789 1966 47.66352572489664 1967 48.041262967140824 1968 49.092499234247164 1969 49.52885233225979 1970 49.44020890016284 1971 49.14160967250497 1972 50.518611091760626 1973 51.07611649707043 1974 51.51519784623219 1975 52.13428987166858 1976 52.68705433116251 1977 53.458445777664934 1978 54.12633637982709 1979 54.735934408238265 1980 55.32637111992398 1981 55.89329983393772 1982 56.4121564162871 1983 56.95714118529173 1984 57.44815715129981 1985 57.85218874643344 1986 58.26227516381462 1987 58.66348097299145 1988 59.09841875176429 1989 59.49179368635632 1990 59.90221014076966 1991 60.08003559527056 1992 60.50789175953553 1993 60.73294098589314 1994 60.99850892422803 1995 61.2696499460086 1996 61.53945841134247 1997 61.99254068647359 1998 62.43419986141296 1999 62.98885745836559 2000 63.33666192499095 2001 63.73242487066275 2002 64.21102492899543 2003 64.67367926632352 2004 65.04510482239166 2005 65.48871776088379 2006 65.97754388498201 2007 66.31488675743067 2008 66.52856510011517 2009 67.02635761527289 2010 67.41546812353403 2011 67.89204568369529 2012 68.32010687508617 2013 68.74352861658406 2014 69.11076198551966 2015 69.45269490449276 2016 69.79706474898431 2017 70.13719708688964 2018 70.36859382667046 2019 70.61562392598276 2020 70.20058149108486 2021 68.49778652742107 2022 69.17397486885034