| Year | Value | | 2017 | 1.0459768346892 | | 2016 | 0.57394801980268 | | 2015 | 0.14568607324097 | | 2014 | 1.1129630337383 | | 2013 | 1.6043929807806 | | 2012 | 2.8273322422262 | | 2011 | 2.8997958430009 | | 2010 | 2.5854181558259 | | 2009 | 2.1995923704601 | | 2008 | 4.293202492877 | | 2007 | 2.498945757258 | | 2006 | 2.0952593561143 | | 2005 | 1.6854889052835 | | 2004 | 1.4308386852734 |
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