| Year | Value | | 2021 | 9.231778663772 | | 2020 | 0.21035604929234 | | 2019 | 3.2095450762868 | | 2018 | 4.9195391203989 | | 2017 | 5.6277757442134 | | 2016 | 4.7959241874469 | | 2015 | 2.5837947845602 | | 2014 | 4.1798725828726 | | 2013 | 4.0818320503316 | | 2012 | 4.4227511133606 | | 2011 | 10.054512617654 | | 2010 | 0.14519232673355 | | 2009 | -13.300826825764 | | 2008 | -4.0263800074507 | | 2007 | 7.5120006033616 | | 2006 | 10.020456715783 | | 2005 | 12.197181645246 | | 2004 | 7.2852395634832 | | 2003 | 8.0805412662627 | | 2002 | 7.6639441714226 | | 2001 | 7.0141674245335 |
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