| Year | Value | | 2016 | 13.632933799029 | | 2015 | 6.332889310942 | | 2014 | 11.502249438201 | | 2013 | 9.6904605452575 | | 2012 | 9.1297178035279 | | 2011 | 16.114301079977 | | 2010 | 0.45014651487223 | | 2009 | 12.392279920241 | | 2008 | 3.3363707131455 | | 2007 | 6.6606915686972 | | 2006 | 9.8062339785745 | | 2005 | 13.096044630252 | | 2004 | 13.929556962923 | | 2003 | 0.77197213845037 | | 2002 | 9.7968608427538 | | 2001 | 17.267302849142 |
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