| Year | Value | | 2021 | 7.1617829383659 | | 2020 | -4.2754360981059 | | 2019 | 4.1945294353124 | | 2018 | 5.5976249576648 | | 2017 | 6.3644580450404 | | 2016 | 5.1455244814139 | | 2015 | 0.40004781306754 | | 2014 | 4.5587234270015 | | 2013 | 0.2969307770005 | | 2012 | -4.9650446442281 | | 2011 | 0.2853674382612 | | 2010 | -1.3893307427387 | | 2009 | -6.4187834040781 | | 2008 | 2.2424991988041 | | 2007 | 7.1508640916823 | | 2006 | 5.3619276496583 | | 2005 | 2.8705341577731 | | 2004 | 3.0418405754478 | | 2003 | 3.2751364682218 | | 2002 | 4.3024056403266 | | 2001 | 4.8767841104799 | | 2000 | 0.16457917427887 | | 1999 | 6.2078650754532 | | 1998 | 3.3501594418606 | | 1997 | 4.9339088896336 | | 1996 | 2.5344409883017 |
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