| Year | Value | | 2021 | 44.011742129343 | | 2020 | 40.564170487338 | | 2019 | 36.043711925444 | | 2018 | 37.752036727653 | | 2017 | 34.51082927866 | | 2016 | 31.362539152361 | | 2015 | 31.67783743277 | | 2014 | 29.858283290289 | | 2013 | 28.987916610904 | | 2012 | 27.913709759147 | | 2011 | 29.185674244057 | | 2010 | 27.371053809155 | | 2009 | 1.3990126157791 | | 2008 | 31.224394828105 | | 2007 | 27.958015267176 | | 2006 | 26.922847662381 | | 2005 | 24.447790248501 |
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