| Year | Value | | 2022 | 61.109196925523 | | 2021 | 60.736334044225 | | 2020 | 60.471396936932 | | 2019 | 60.432385685121 | | 2018 | 60.50463487498 | | 2017 | 60.812011117962 | | 2016 | 60.949235432167 | | 2015 | 61.157561430608 | | 2014 | 61.832123789443 | | 2013 | 62.150613168824 | | 2012 | 62.866663698216 | | 2011 | 63.534125145679 | | 2010 | 61.63207439386 |
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