| Year | Value | | 2021 | 8.6149950941652 | | 2020 | -7.5123479876729 | | 2019 | 4.589569334309 | | 2018 | 2.5400004548858 | | 2017 | 6.1490680487421 | | 2016 | 9.9533146525112 | | 2015 | -8.6393213110089 | | 2014 | 5.6375849489284 | | 2013 | 7.9296649403533 | | 2012 | 3.9285300250502 | | 2011 | 8.7669564638406 | | 2010 | 17.598639048133 | | 2009 | -8.0821464945831 | | 2008 | 6.6430816186501 | | 2007 | 1.9145840061368 | | 2006 | 3.7477092325601 | | 2005 | 8.0901854946067 | | 2004 | 9.6399304119641 | | 2003 | 12.891230192419 | | 2002 | 14.616607441203 | | 2001 | 13.486304527907 | | 2000 | 10.981692443734 | | 1999 | -10.272366425063 | | 1998 | -8.6117690408576 | | 1997 | 4.632156787271 |
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