| Year | Value | | 2019 | 2.3023725151682 | | 2018 | 0.62614914916898 | | 2017 | 4.9759515055389 | | 2016 | 4.3838919551389 | | 2015 | 0.66170916471352 | | 2014 | 4.6739960353631 | | 2013 | 7.3857717839785 | | 2012 | 6.4412128093412 | | 2011 | 11.804185808913 | | 2010 | 2.1785375238941 | | 2009 | -6.8111610889899 | | 2008 | 26.418664154745 | | 2007 | 8.680570785134 | | 2006 | 6.7845965500166 | | 2005 | 12.686268721671 |
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