| Year | Value | | 2021 | 10.194450616503 | | 2020 | 9.9266538403886 | | 2019 | 10.463157391763 | | 2018 | 10.864887715808 | | 2017 | 10.926325248983 | | 2016 | 10.698370363065 | | 2015 | 10.994757145696 | | 2014 | 11.498283711249 | | 2013 | 11.68952111277 | | 2012 | 11.95899201838 | | 2011 | 12.16977062586 | | 2010 | 12.032150789101 | | 2009 | 11.731148626167 | | 2008 | 12.206294831376 | | 2007 | 12.048162099811 | | 2006 | 11.487991819768 | | 2005 | 11.057127508302 |
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