Year | Value | 2023 | 26.563905140496 | 2022 | 30.029747010057 | 2021 | 30.622391762394 | 2020 | 27.073287841133 | 2019 | 26.391305428541 | 2018 | 27.987925246388 | 2017 | 26.056865090415 | 2016 | 24.981909333024 | 2015 | 25.214418163276 | 2014 | 24.899948758654 | 2013 | 23.911736241161 | 2012 | 23.380426650592 | 2011 | 23.027270950755 | 2010 | 21.797639725187 | 2009 | 21.949702204576 | 2008 | 24.620375305765 | 2007 | 23.912255777434 | 2006 | 24.626761994941 | 2005 | 23.640360306821 | 2004 | 22.306732865773 | 2003 | 20.653712441418 | 2002 | 22.452599204927 | 2001 | 21.520088245783 | 2000 | 21.403969624397 | 1999 | 21.819944632185 | 1998 | 25.731235828247 | 1997 | 20.492078130626 | 1996 | 21.800704445056 | 1995 | 19.609096533248 | 1994 | 18.191319313568 | 1993 | 18.513951818464 | 1992 | 18.348793818733 | 1991 | 18.552669829995 | 1990 | 21.691362290051 | 1989 | 26.076821222933 | 1988 | 28.425803930369 | 1987 | 24.171653825719 | 1986 | 38.402916641379 | 1985 | 34.822732259122 | 1984 | 29.402416682199 | 1983 | 28.805822031095 | 1982 | 31.864356379024 | 1981 | 32.51284647513 | 1980 | 28.824322257485 | 1979 | 33.705698139016 | 1978 | 30.930653012201 | 1977 | 31.930985515479 | 1976 | 34.099125364432 | 1975 | 32.7876202296 | 1974 | 32.149052037112 |
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