| Year | Value | | 2022 | 15.100165146837 | | 2021 | 3.8398449150015 | | 2020 | 3.161295284978 | | 2019 | 2.8478759591805 | | 2018 | 2.1494949494949 | | 2017 | 2.4505339846014 | | 2016 | 0.6835042093857 | | 2015 | 0.30936454849498 | | 2014 | 0.34398858964679 | | 2013 | 1.4382978723404 | | 2012 | 3.2876230661041 | | 2011 | 1.9172191363555 | | 2010 | 1.4727272727272 | | 2009 | 1.0193773532923 | | 2008 | 6.3586638015237 | | 2007 | 2.8531243721118 | | 2006 | 2.5339925834363 | | 2005 | 1.8570978910922 | | 2004 | 2.7601078167116 | | 2003 | 0.11873920552679 | | 2002 | 1.9029809701903 | | 2001 | 4.6626755698825 | | 2000 | 3.7753882915173 | | 1999 | 2.1354484441733 | | 1998 | 10.698365527489 | | 1997 | 8.5961566671556 | | 1996 | 8.7587747287811 | | 1995 | 8.9905236147845 | | 1994 | 10.039429835143 | | 1993 | 20.813029543843 | | 1992 | 11.086500072223 |
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