Year | Value | 2021 | 19.416839494704 | 2020 | 18.384216978044 | 2019 | 18.081450414677 | 2018 | 18.128923536318 | 2017 | 17.753751064506 | 2016 | 17.354775618928 | 2015 | 16.752684909405 | 2014 | 16.708795201976 | 2013 | 17.054735218472 | 2012 | 16.182435828796 | 2011 | 15.344033508547 | 2010 | 15.812080711538 | 2009 | 14.977030523327 | 2008 | 17.060203292509 | 2007 | 16.744896909489 | 2006 | 15.670107731991 | 2005 | 14.51081779834 | 2004 | 12.654454860285 | 2003 | 12.678297094566 | 2002 | 12.099470741529 | 2001 | 13.30670082596 | 2000 | 10.605495695998 | 1999 | 10.43175690747 | 1998 | 9.8797898252374 |
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