| Year | Value | | 2022 | 37.503650183158 | | 2021 | 33.106531589172 | | 2020 | 33.389438653303 | | 2019 | 34.575649852707 | | 2018 | 35.447352040736 | | 2017 | 32.154767833319 | | 2016 | 24.378961831161 | | 2015 | 25.793684255738 | | 2014 | 30.30217411731 | | 2013 | 29.491028119465 | | 2012 | 32.681197668518 | | 2011 | 33.655773808802 | | 2010 | 31.71918699119 | | 2009 | 35.822311528657 | | 2008 | 48.55826465629 | | 2007 | 39.840454828353 | | 2006 | 37.454772133769 | | 2005 | 34.672480521243 |
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