| Year | Value | | 2022 | 27.565497551458 | | 2021 | 29.314176275754 | | 2020 | 29.214580493816 | | 2019 | 27.83472652762 | | 2018 | 26.769768287281 | | 2017 | 26.342632963115 | | 2016 | 27.118918315289 | | 2015 | 25.653313386418 | | 2014 | 25.986131228843 | | 2013 | 25.484161161239 | | 2012 | 25.775117638696 | | 2011 | 26.094530328553 | | 2010 | 25.824894730564 | | 2009 | 24.839527312545 | | 2008 | 28.701351801188 | | 2007 | 28.189830770091 | | 2006 | 26.735948396423 | | 2005 | 26.056628480125 |
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