| Year | Value | | 2021 | 8.3737084877195 | | 2020 | -2.1805601494682 | | 2019 | 6.4098400182812 | | 2018 | 2.0793099549266 | | 2017 | 3.9130085016937 | | 2016 | 5.2549834439952 | | 2015 | 2.1720569209653 | | 2014 | 2.2376191005672 | | 2013 | -1.4418719246436 | | 2012 | 2.2916551001698 | | 2011 | 3.8654583820777 | | 2010 | 1.2406221986428 | | 2009 | 0.68341118725283 | | 2008 | 11.220911772624 | | 2007 | 2.9953791493358 | | 2006 | 4.9224186186588 | | 2005 | 4.9670879146989 | | 2004 | 7.5680146711116 | | 2003 | 4.7334036124295 | | 2002 | 8.1496280456715 | | 2001 | 7.4340402940595 | | 2000 | 3.7708340622078 | | 1999 | -7.7190795925544 | | 1998 | 2.9786775240671 | | 1997 | -22.537065017589 | | 1996 | -1.9960396670712 |
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