Year | Value | 2021 | 5.6847955456445 | 2020 | 8.9017283250798 | 2019 | 15.405390526761 | 2018 | 15.325405456931 | 2017 | 15.359881763705 | 2016 | 13.525356893396 | 2015 | 13.465051283569 | 2014 | 14.109565884041 | 2013 | 14.066114453475 | 2012 | 15.198026622529 | 2011 | 16.377332913785 | 2010 | 16.844476685071 | 2009 | 16.856306005744 | 2008 | 16.418394000229 | 2007 | 14.944119165497 | 2006 | 15.008285536825 | 2005 | 15.168103772455 | 2004 | 16.508643948637 | 2003 | 15.37671345995 | 2002 | 14.430590191189 | 2001 | 11.87807719773 | 2000 | 11.901229823213 | 1999 | 13.372688098234 | 1998 | 12.633228804161 | 1997 | 11.932725773196 |
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