| Year | Value | | 2021 | 26.459079047831 | | 2020 | 22.441779002689 | | 2019 | 14.487707948583 | | 2018 | 15.841595210893 | | 2017 | 21.649945297508 | | 2016 | 10.854372326875 | | 2015 | 12.309062850905 | | 2014 | 15.393134688337 | | 2013 | 12.539249751773 | | 2012 | 8.1580007999076 | | 2011 | 19.168138341316 | | 2010 | 19.940357952442 | | 2009 | 8.5436361628573 | | 2008 | 3.4531866460511 | | 2007 | 13.070581204596 | | 2006 | 11.825032898486 | | 2005 | 7.3624217532321 |
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