| Year | Value | | 2022 | 10.390894275608 | | 2021 | 3.2532892478204 | | 2020 | 1.2057546336348 | | 2019 | 1.8166904095746 | | 2018 | 2.0406123146816 | | 2017 | 1.9560763336396 | | 2016 | 0.39180380179113 | | 2015 | 0.41004049800847 | | 2014 | 0.62451731108657 | | 2013 | 1.7506819593704 | | 2012 | 2.7733385405159 | | 2011 | 3.8561124468282 | | 2010 | 2.4244736179163 | | 2009 | 1.5360765001428 | | 2008 | 6.0597404633971 | | 2007 | 2.9159826187286 | | 2006 | 3.1928863780875 | | 2005 | 2.6093230819775 | | 2004 | 2.8294779621466 | | 2003 | 2.3486416958276 | | 2002 | 2.7861598858951 | | 2001 | 4.262872288737 | | 2000 | 3.7753882915173 | | 1999 | 2.3648183611181 | | 1998 | 4.6442142266079 | | 1997 | 5.5360026677348 | | 1996 | 8.1945521763273 | | 1995 | 8.9625188871998 | | 1994 | 12.144798011569 | | 1993 | 14.411264443935 | | 1992 | 5.9245312622849 |
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