Year | Value | 2022 | 18.344846059578 | 2021 | 18.593142800395 | 2020 | 18.839550872485 | 2019 | 19.087669201881 | 2018 | 19.330116085859 | 2017 | 19.573808740147 | 2016 | 19.829667393001 | 2015 | 20.092935503946 | 2014 | 20.361271420559 | 2013 | 20.632698040831 | 2012 | 20.906365824569 | 2011 | 21.185436586075 | 2010 | 21.473357682987 | 2009 | 21.756819646546 | 2008 | 22.047972181272 | 2007 | 22.346745817123 | 2006 | 22.652303593732 | 2005 | 22.961758574696 | 2004 | 23.274017185282 | 2003 | 23.591201744207 | 2002 | 23.920483714312 | 2001 | 24.256902680594 | 2000 | 24.623491908405 | 1999 | 25.0825342191 | 1998 | 25.54657352737 | 1997 | 26.027512000786 | 1996 | 26.514556103241 | 1995 | 26.993433304329 | 1994 | 27.495530709733 | 1993 | 28.002959914359 | 1992 | 28.504259789007 | 1991 | 29.018385222417 | 1990 | 29.552299607202 | 1989 | 30.111395991789 | 1988 | 30.682154710118 | 1987 | 31.262631000538 | 1986 | 31.84986347798 | 1985 | 32.447286277631 | 1984 | 33.057959902549 | 1983 | 33.673080674296 | 1982 | 34.292994676537 | 1981 | 34.930103415678 | 1980 | 35.594367637484 | 1979 | 36.297023005971 | 1978 | 37.009316254522 | 1977 | 37.72827693018 | 1976 | 38.449162584702 | 1975 | 39.169284666455 | 1974 | 39.893049013328 | 1973 | 40.616743438286 | 1972 | 41.345732384062 | 1971 | 42.097656822097 | 1970 | 42.859989141768 | 1969 | 43.630733605369 | 1968 | 44.406642330255 | 1967 | 45.187132258035 | 1966 | 45.966873096326 | 1965 | 46.747608626748 | 1964 | 47.528719111433 | 1963 | 48.367282722606 | 1962 | 49.200992567249 | 1961 | 50.031910565463 | 1960 | 50.84999550111 |
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