| Year | Value | | 2022 | 2.8118409747716 | | 2021 | 1.5466370558375 | | 2020 | 0.90387487227849 | | 2019 | 0.13379505745313 | | 2018 | 0.88130210400948 | | 2017 | 1.5971606033719 | | 2016 | 1.1092080580703 | | 2015 | 0.065290133028709 | | 2014 | 1.0223431445296 | | 2013 | 1.0455283875536 | | 2012 | 2.9477349525721 | | 2011 | 4.042188671164 | | 2010 | 3.2565795907862 | | 2009 | 3.468810237549 | | 2008 | 12.375409152991 | | 2007 | 5.8304841809271 | | 2006 | 3.5449859160503 | | 2005 | 1.9098355353187 | | 2004 | 0.62496906263134 | | 2003 | 0.2313286822671 | | 2002 | 0.27957882257134 | | 2001 | 0.81666666666667 |
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