| Year | Value | | 2021 | 12.063029098857 | | 2020 | 13.252029069375 | | 2019 | 13.017421488345 | | 2018 | 14.5607153724 | | 2017 | 15.663721917107 | | 2016 | 14.702873616665 | | 2015 | 15.283214054981 | | 2014 | 15.196512569369 | | 2013 | 16.901703589527 | | 2012 | 16.574500043782 | | 2011 | 16.01833722906 | | 2010 | 17.019206611754 | | 2009 | 18.000158603851 | | 2008 | 18.313102841144 | | 2007 | 17.319934810165 | | 2006 | 17.522562804849 | | 2005 | 17.286787242113 | | 2004 | 15.721558335886 | | 2003 | 15.672509293748 | | 2002 | 15.77179136949 |
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