| Year | Value | | 2021 | 40.73945625779 | | 2020 | 39.274557488344 | | 2019 | 38.44677841577 | | 2018 | 40.341624249359 | | 2017 | 40.482838332891 | | 2016 | 39.319753286877 | | 2015 | 39.947204957727 | | 2014 | 39.633283287671 | | 2013 | 40.04899793166 | | 2012 | 39.406316325167 | | 2011 | 36.950642718298 | | 2010 | 38.494107681527 |
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