| Year | Value | | 2021 | 4.8791024638849 | | 2020 | -6.8617295920014 | | 2019 | 1.2352072794852 | | 2018 | 0.41402731719653 | | 2017 | 3.2011691638026 | | 2016 | 0.37390701958128 | | 2015 | 0.99927544106313 | | 2014 | 1.2742789590475 | | 2013 | 3.4929480000165 | | 2012 | 1.4014347702605 | | 2011 | 4.1680223340435 | | 2010 | 6.638192228423 | | 2009 | -1.9781129672793 | | 2008 | 2.7989334225703 | | 2007 | 6.5702287151354 | | 2006 | 7.7630267920051 | | 2005 | 2.877427504152 | | 2004 | 4.3293247989131 | | 2003 | 1.3992599131262 | | 2002 | 0.51818002687889 | | 2001 | 0.47945465556933 | | 2000 | 2.5930303663289 | | 1999 | 0.76640340733476 | | 1998 | 2.0866004017726 | | 1997 | 5.6360244784497 | | 1996 | 3.2398516161995 | | 1995 | 2.3941700239281 | | 1994 | 11.863234302868 | | 1993 | 2.6874503202007 | | 1992 | 4.0897822657177 | | 1991 | 6.1278476718965 | | 1990 | -2.1877909204569 |
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