Year | Value | 2021 | 14.014128455911 | 2020 | 13.112430243553 | 2019 | 13.470228138661 | 2018 | 13.515025654232 | 2017 | 13.394230720948 | 2016 | 13.712497602413 | 2015 | 13.661730597474 | 2014 | 13.140906583231 | 2013 | 13.221980249186 | 2012 | 13.227861274308 | 2011 | 13.537908650089 | 2010 | 13.052427217271 |
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