| Year | Value | | 2022 | 13.0403036347 | | 2021 | 2.4108019840317 | | 2020 | 0.25565569984855 | | 2019 | 0.36156370454077 | | 2018 | 2.611223782638 | | 2017 | 2.3802359905313 | | 2016 | 0.27138502338518 | | 2015 | 1.5486915822249 | | 2014 | 0.71051405171023 | | 2013 | 2.2058926814118 | | 2012 | 4.1452472498112 | | 2011 | 3.4501431124869 | | 2010 | 0.65494657014848 | | 2009 | 3.4667237320779 | | 2008 | 8.758727695888 | | 2007 | 4.3471221565611 | | 2006 | 2.9245125812365 |
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