| Year | Value | | 2022 | 4.8278885959448 | | 2021 | 0.013859944401224 | | 2020 | -2.0794031794098 | | 2019 | -1.9310811478215 | | 2018 | 3.0686337925201 | | 2017 | 1.9668255781886 | | 2016 | 1.6174880890419 | | 2015 | 4.069966083616 | | 2014 | 2.3462686567163 | | 2013 | 1.1011183637571 | | 2012 | 0.66226890026911 | | 2011 | 0.87734659568502 | | 2010 | 0.877983288286 | | 2009 | 1.5618131744906 | | 2008 | 12.250420244814 |
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