Year years 1960 40.74320268298056 1961 41.071671970274906 1962 41.62237665312326 1963 41.76393400638191 1964 42.253055775010296 1965 42.401398566517535 1966 42.33486772330063 1967 42.976579370782495 1968 43.30820644319975 1969 43.56528346657549 1970 43.87857391382499 1971 44.223790242607215 1972 44.02369655049331 1973 44.76052282894577 1974 44.79944872176096 1975 45.1666195224371 1976 45.84417819976955 1977 46.212474584880056 1978 46.39335832235114 1979 46.80426001726009 1980 47.214725632848975 1981 47.51565661473694 1982 47.737663741172774 1983 46.52564001177554 1984 46.397441235739045 1985 46.76065819959353 1986 47.57774115764353 1987 48.30188300595508 1988 48.10638923331893 1989 49.17537501110079 1990 49.21020591692235 1991 49.20819670291272 1992 49.187801844134206 1993 49.79599985250528 1994 50.16104123290726 1995 50.66783570813712 1996 50.78845500003173 1997 51.136526791931146 1998 50.95230415305459 1999 51.8352413766677 2000 52.66175412095464 2001 53.13109920509466 2002 53.62999651695246 2003 54.229668876523945 2004 54.740409284175044 2005 55.40832281769307 2006 56.233620674672544 2007 56.88988798930103 2008 57.50407018553205 2009 58.24031169505169 2010 58.57768856792502 2011 59.47522039825314 2012 60.07801762292335 2013 60.64456075370131 2014 61.14707309305527 2015 61.61254772939035 2016 62.16196194022386 2017 62.54976046880772 2018 62.947575947408374 2019 63.33805694716437 2020 62.76172018146169 2021 62.30278539996223 2022 62.843246261160665