Year | Value | 2021 | 15.874209881547 | 2020 | 19.45223514151 | 2019 | 22.892848860567 | 2018 | 23.993353427438 | 2017 | 24.669942083547 | 2016 | 23.534623589903 | 2015 | 23.615705535352 | 2014 | 22.643755989562 | 2013 | 23.475662746065 | 2012 | 22.892576135079 | 2011 | 22.917093317277 | 2010 | 21.822564421384 | 2009 | 21.74935566048 | 2008 | 22.713629311817 | 2007 | 19.209669842466 | 2006 | 23.386279249676 | 2005 | 21.536011904762 | 2004 | 22.349214804713 | 1996 | 21.207820032137 | 1995 | 22.206142408604 | 1994 | 21.490030301897 | 1993 | 21.40218037661 | 1992 | 21.592566863494 | 1991 | 21.871694417238 | 1990 | 22.757070707071 |
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