| Year | Value | | 2022 | 17.353061559359 | | 2021 | 17.432283897733 | | 2020 | 5.2286987236825 | | 2019 | 17.68758296668 | | 2018 | 14.896031546862 | | 2017 | 14.155195113288 | | 2016 | 9.8617868685605 | | 2015 | 9.115146094577 | | 2014 | 7.7994541202911 | | 2013 | 8.2174161962393 | | 2012 | 5.1310203441208 | | 2011 | 4.2749712810759 | | 2010 | 1.1667822113963 | | 2009 | 0.75975731957368 | | 2008 | -8.2902914024508 | | 2007 | -4.5969815882656 |
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