| Year | Value | | 2021 | 11.117038404873 | | 2020 | -3.4665022897134 | | 2019 | 10.13682922288 | | 2018 | 8.4380245282093 | | 2017 | 3.3157564205733 | | 2016 | 4.7969541788833 | | 2015 | 11.424697802767 | | 2014 | 6.870981138702 | | 2013 | 4.3948534313946 | | 2012 | 7.718334361109 | | 2011 | 9.4356467828778 | | 2010 | 6.945363213229 | | 2009 | 8.4857791350999 | | 2008 | 1.1742368389957 | | 2007 | 7.4586543821856 | | 2006 | 14.539962079502 | | 2005 | 11.46954536406 | | 2004 | 11.329148668422 | | 2003 | -3.7696329365635 | | 2002 | 11.826012398776 | | 2001 | 5.5503904623367 | | 2000 | 12.989833989559 | | 1999 | 27.070549686272 | | 1998 | 8.0962749609058 | | 1997 | 23.013631840678 | | 1996 | 9.6420057180535 | | 1995 | 54.952605317066 | | 1994 | -60.245828952674 | | 1993 | -5.949076208248 | | 1992 | 2.496642822216 | | 1991 | 5.9956023832118 | | 1990 | 0.3023375058516 | | 1989 | -1.6395171859722 | | 1988 | 8.3959101407437 | | 1987 | -6.2781086426984 | | 1986 | 7.5817821297799 | | 1985 | 0.71361761875018 | | 1984 | -6.2301315971313 | | 1983 | 14.734593325105 | | 1982 | -1.3811347417869 | | 1981 | 11.911188926382 |
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