| Year | Value | | 2021 | 14.071 | | 2020 | 8.101 | | 2019 | 13.313 | | 2018 | 17.7117 | | 2017 | 7.355192 | | 2016 | 4.737729 | | 2015 | 3.217 | | 2014 | 2.748 | | 2013 | 1.451004 | | 2012 | 1.45 | | 2011 | 2.234 | | 2010 | 2.133 | | 2009 | 2.011 | | 2008 | 3.412 | | 2007 | 3.79 | | 2006 | 4.114 | | 2005 | 4.578 | | 2004 | 5.892 | | 2003 | 4.454 | | 2002 | 4.418 | | 2001 | 4.008 |
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