| Year | Value | | 2017 | 2.1920101096298 | | 2016 | 0.11168265573758 | | 2015 | 0.33002716514107 | | 2014 | 1.8867546627527 | | 2013 | 2.5286478853837 | | 2012 | 4.0151842108158 | | 2011 | 4.584754356504 | | 2010 | 1.3385762167288 | | 2009 | 5.957636887608 | | 2008 | 0.41792902008076 | | 2007 | 4.4324575424575 | | 2006 | 0.3006012024048 |
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