| Year | Value | | 2021 | 11.709761019193 | | 2020 | 10.685990251984 | | 2019 | 10.77057935076 | | 2018 | 11.283826646637 | | 2017 | 11.742933213244 | | 2016 | 28.923008045508 | | 2015 | 27.925711751511 | | 2014 | 26.76237699877 | | 2013 | 26.897944160417 | | 2012 | 29.74084705529 | | 2011 | 30.333521060187 | | 2010 | 31.470229783453 | | 2009 | 32.116065833325 | | 2008 | 34.334866743215 | | 2007 | 35.633235633792 | | 2006 | 39.929472164704 | | 2005 | 42.511612277643 | | 2004 | 41.866757768466 | | 2003 | 34.874481101487 | | 2002 | 42.508690919118 | | 2001 | 43.236293528665 |
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