| Year | Value | | 2019 | 85.172448955537 | | 2018 | 83.835708531217 | | 2017 | 78.041916249333 | | 2016 | 66.415584316513 | | 2015 | 62.00562782892 | | 2014 | 21.528026904358 | | 2013 | 22.911215930211 | | 2012 | 26.864699728335 | | 2011 | 25.511966494881 | | 2010 | 32.385855813015 | | 2009 | 23.956162058677 | | 2008 | 23.260505862539 |
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