Year | Value | 2022 | 18.777571655948 | 2021 | 19.041285862433 | 2020 | 19.307956115314 | 2019 | 19.578146461032 | 2018 | 19.850104218421 | 2017 | 20.124836148235 | 2016 | 20.404062547445 | 2015 | 20.687076463094 | 2014 | 20.974431347652 | 2013 | 21.264929976381 | 2012 | 21.558233101227 | 2011 | 21.857694745575 | 2010 | 22.165653731727 | 2009 | 22.467858524429 | 2008 | 22.778332005182 | 2007 | 23.096817706163 | 2006 | 23.42245163779 | 2005 | 23.752105860453 | 2004 | 24.084739066437 | 2003 | 24.422449805151 | 2002 | 24.774433705184 | 2001 | 25.12953170947 | 2000 | 25.5016760587 | 1999 | 25.969027769166 | 1998 | 26.440419320519 | 1997 | 26.929263153244 | 1996 | 27.422825842821 | 1995 | 27.905862858938 | 1994 | 28.413143969951 | 1993 | 28.925234323378 | 1992 | 29.429760440963 | 1991 | 29.952652869901 | 1990 | 30.500286829289 | 1989 | 31.078193858122 | 1988 | 31.668399499472 | 1987 | 32.268909497996 | 1986 | 32.876644081317 | 1985 | 33.495892300966 | 1984 | 34.130146900236 | 1983 | 34.769605764012 | 1982 | 35.414357584063 | 1981 | 36.066118612016 | 1980 | 36.746555980226 | 1979 | 37.466128429598 | 1978 | 38.195594653468 | 1977 | 38.931832483744 | 1976 | 39.669476158959 | 1975 | 40.405466988188 | 1974 | 41.147294912838 | 1973 | 41.889499052022 | 1972 | 42.637523794043 | 1971 | 43.407887349745 | 1970 | 44.180964071116 | 1969 | 44.941631450663 | 1968 | 45.706548740954 | 1967 | 46.475003002947 | 1966 | 47.242019051801 | 1965 | 48.009254157621 | 1964 | 48.776207683727 | 1963 | 49.60363712026 | 1962 | 50.424694723703 | 1961 | 51.241091069373 | 1960 | 52.032909827427 |
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