| Year | Value | | 2021 | 5.7188932054812 | | 2020 | 3.1972617495899 | | 2019 | 3.9217341327779 | | 2018 | 5.8497974788744 | | 2017 | 0.51293723496744 | | 2016 | 2.5350551681566 | | 2015 | 0.71249746408167 | | 2014 | 0.40063305732154 | | 2013 | 5.8133601777299 | | 2012 | -1.6487270373461 | | 2011 | -1.0652242086851 | | 2010 | -2.881889653727 | | 2009 | 0.637907321794 | | 2008 | 5.8942636309172 | | 2007 | 8.4253376144821 |
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