Year | Value | 2021 | 18.93023868237 | 2020 | 19.180078935218 | 2019 | 19.579348667521 | 2018 | 20.055532774301 | 2017 | 20.361748182342 | 2016 | 20.840861594434 | 2015 | 21.227371193985 | 2014 | 21.590738770603 | 2013 | 22.151091950633 | 2012 | 22.502719018831 | 2011 | 22.822200185514 | 2010 | 23.153487806287 | 2009 | 23.505571635291 | 2008 | 23.82891340976 | 2007 | 24.126371453556 | 2006 | 24.375094752376 | 2005 | 24.799054499851 | 2004 | 25.299727283129 | 2003 | 25.746494948726 | 2002 | 26.288504491307 | 2001 | 26.812155577163 | 2000 | 27.10469712751 | 1999 | 27.476613537684 | 1998 | 27.963264967088 | 1997 | 28.482773100555 | 1996 | 29.022684215142 | 1995 | 29.632067064277 | 1994 | 30.232536298437 | 1993 | 30.807566687201 | 1992 | 31.473243498143 | 1991 | 32.114664361029 | 1990 | 32.615530034602 | 1989 | 33.334356869878 | 1988 | 34.004259276596 | 1987 | 34.624102395452 | 1986 | 35.315111831683 | 1985 | 35.727679491842 | 1984 | 36.308855610616 | 1983 | 36.665003061583 | 1982 | 37.046151938429 | 1981 | 37.35902130525 | 1980 | 37.622738294106 | 1979 | 37.814293619469 | 1978 | 37.982538043051 | 1977 | 38.314388286591 | 1976 | 38.829730357824 | 1975 | 39.11969920327 | 1974 | 39.636466062719 | 1973 | 40.024089046265 | 1972 | 40.349719999397 | 1971 | 40.675703433552 | 1970 | 40.891909184787 | 1969 | 41.184968039482 | 1968 | 41.542327266612 | 1967 | 41.926647613639 | 1966 | 42.307792201516 | 1965 | 42.729253251109 | 1964 | 43.108054689714 | 1963 | 43.380252878628 | 1962 | 43.652521579093 | 1961 | 43.864575568529 | 1960 | 44.061863277235 |
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