| Year | Value | | 2021 | 1.6946247354477 | | 2020 | -7.5055323966707 | | 2019 | 3.924811734942 | | 2018 | -2.2386478682921 | | 2017 | 4.4247783514363 | | 2016 | -3.9611351476425 | | 2015 | -10.012534714248 | | 2014 | -2.0225986116832 | | 2013 | 0.14290225851235 | | 2012 | 7.1749783707621 | | 2011 | 16.244847224006 | | 2010 | 2.0293707337783 | | 2009 | -16.449354679996 | | 2008 | 24.855162609592 | | 2007 | 4.2854691967586 | | 2006 | 9.438673846252 | | 2005 | 13.549998504653 | | 2004 | 12.071022983246 | | 2003 | 1.9863801854837 | | 2002 | 11.881919809085 | | 2001 | 3.7985571515858 | | 2000 | 4.1169739387482 | | 1999 | 5.4051700736446 | | 1998 | -6.6363768887709 | | 1997 | -17.564441962256 | | 1996 | 35.960847659263 | | 1995 | -2.5108317842977 | | 1994 | -5.7733489215439 | | 1993 | -4.7206513201407 | | 1992 | 2.0939827311909 | | 1991 | 13.548247927823 |
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