Year years 1960 42.7231428623187 1961 43.195550285380165 1962 43.69148351398484 1963 43.846102463578276 1964 44.534336158763196 1965 44.55655299474613 1966 44.94214210945094 1967 45.51678944831293 1968 45.88256536874679 1969 46.138980968356044 1970 45.04983731145693 1971 42.292114215821805 1972 46.69505895703211 1973 47.255800304258806 1974 47.26268210835678 1975 47.306924438522536 1976 47.915195883400884 1977 48.58224602589514 1978 48.95038549774191 1979 49.41182161033092 1980 49.908030388165045 1981 50.200001295735056 1982 50.41478228792704 1983 49.94332067188398 1984 50.04692068786822 1985 50.397256963205535 1986 51.02299449517685 1987 51.588752923955745 1988 51.467387172958524 1989 52.35084302283997 1990 52.65378730861273 1991 52.37482821318062 1992 52.94832062994237 1993 53.413255217203925 1994 53.998811850833675 1995 54.41116179762028 1996 54.543363671766286 1997 55.17993948505876 1998 55.41284617862207 1999 56.608641036422945 2000 57.066160858641986 2001 57.515275925664085 2002 57.95028267622472 2003 58.453630548084476 2004 58.77345726241524 2005 59.387415914187734 2006 59.942639801517544 2007 60.34717017576683 2008 60.476374771829256 2009 61.327997604479144 2010 61.82756744921935 2011 62.47208474573782 2012 62.848514616804124 2013 63.19409575872412 2014 63.577512752047355 2015 63.95788920578941 2016 64.47164293263903 2017 64.87272864871503 2018 65.27719305985798 2019 65.64179339728979 2020 65.10590483040735 2021 64.74778514269326 2022 65.41607448651483