| Year | Value | | 2021 | 27.33694319 | | 2020 | 21.16321517 | | 2019 | 16.38375122 | | 2017 | 8.478170295 | | 2016 | 7.938322771 | | 2015 | 7.459161386 | | 2014 | 6.98 | | 2013 | 6.5 | | 2012 | 5.975296308 | | 2011 | 5.5 | | 2010 | 5.1 | | 2009 | 3.5 | | 2008 | 3 | | 2007 | 2.5 | | 2006 | 2.2 | | 2005 | 2 | | 2004 | 1.327327178 | | 2003 | 0.84818937 | | 2002 | 0.554869675 | | 2001 | 0.443068373 | | 2000 | 0.271740607 | | 1999 | 0.148162964 | | 1998 | 0.03787097 |
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