| Year | Value | | 2021 | 2.4027779704016 | | 2020 | -9.1125681318497 | | 2019 | 5.7562817827892 | | 2018 | 4.1346141146796 | | 2017 | 10.356492439866 | | 2016 | -1.4648343131018 | | 2015 | -1.4106510915707 | | 2014 | 1.2323718854572 | | 2013 | 3.4592603075599 | | 2012 | 13.079423987122 | | 2011 | 2.6870077558226 | | 2010 | 1.5901956113687 | | 2009 | -21.953139935498 | | 2008 | 9.2782318447876 | | 2007 | 16.88731878184 | | 2006 | 14.627131761445 | | 2005 | 14.873202083584 | | 2004 | 10.338224466054 | | 2003 | 19.839445735789 | | 2002 | 14.783654018807 | | 2001 | 8.3306469502991 | | 2000 | 0.86766463912845 | | 1999 | 3.1391521368458 | | 1998 | 3.5654795633294 | | 1997 | 6.8988010511555 | | 1996 | 6.4384383900622 |
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