Year | Value | 2022 | 26.582498749512 | 2021 | 25.447136010014 | 2020 | 25.843348060996 | 2019 | 27.160951879279 | 2018 | 27.868440316515 | 2017 | 27.665998623944 | 2016 | 27.39954585851 | 2015 | 27.696532424043 | 2014 | 28.701768655301 | 2013 | 29.167937637176 | 2012 | 29.858504741939 | 2011 | 30.42378300729 | 2010 | 31.394751219608 | 2009 | 30.141418037006 | 2008 | 31.962008175119 | 2007 | 32.538747245102 | 2006 | 32.385673384705 | 2005 | 30.881502682427 | 2004 | 29.597500808525 | 2003 | 27.263374807015 | 2002 | 26.087004134615 | 2001 | 25.058003777783 | 2000 | 25.84879893004 | 1999 | 25.72216451954 | 1998 | 24.474908434986 | 1997 | 24.790990677795 | 1996 | 24.872806520121 | 1995 | 24.945522771316 | 1994 | 25.064898196621 | 1993 | 24.06903859471 | 1992 | 22.637595506636 | 1991 | 22.359817201448 | 1990 | 21.724604997507 | 1989 | 20.006010916719 | 1988 | 19.126324047429 | 1987 | 18.72040881217 | 1986 | 17.322844373032 | 1985 | 18.213956532728 | 1984 | 18.603326988477 | 1983 | 19.602835940555 | 1982 | 19.146203915524 | 1981 | 19.296385179046 | 1980 | 17.428645632705 | 1979 | 18.294609417451 | 1978 | 17.260579698398 | 1977 | 18.60685382023 |
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