| Year | Value | | 2021 | -3.4435356224942 | | 2020 | 6.3637256702157 | | 2019 | 6.9475831248804 | | 2018 | 9.4669872651976 | | 2017 | 3.7281246437537 | | 2016 | 6.6493962061183 | | 2015 | 1.7055319786818 | | 2014 | -4.4608916640947 | | 2013 | 14.156122272875 | | 2012 | 10.94946675692 | | 2011 | 9.2447638112298 | | 2010 | 3.8100938641453 | | 2009 | -2.7706255147293 | | 2008 | 9.8074789118136 | | 2007 | 7.1689097194059 |
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