| Year | Value | | 2022 | 14.170198887576 | | 2021 | 15.68227721725 | | 2020 | 10.787849029758 | | 2019 | 14.874645148185 | | 2018 | 12.021225993117 | | 2017 | 14.361829118389 | | 2016 | 10.557630898894 | | 2015 | 9.8767718294936 | | 2014 | 11.784271058427 | | 2013 | 16.50880368348 | | 2012 | 13.664076327758 | | 2011 | 17.256569354322 | | 2010 | 13.381159585504 |
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