| Year | Value | | 2021 | 6.4322455070514 | | 2020 | -2.2309777989987 | | 2019 | 3.2937095194281 | | 2018 | 3.5548165801735 | | 2017 | 5.5814241702438 | | 2016 | 5.1527648516112 | | 2015 | 4.1821586989388 | | 2014 | 5.0669580465615 | | 2013 | 4.5331494696609 | | 2012 | 5.8449182495748 | | 2011 | 4.9635144363496 | | 2010 | 8.1258564467396 | | 2009 | 4.7106502382303 | | 2008 | 4.1303021664521 | | 2007 | 15.209690819479 | | 2006 | 11.488764983685 | | 2005 | 6.8670841735382 | | 2004 | 12.733940116544 | | 2003 | 0.28533925043126 | | 2002 | 13.022003828835 | | 2001 | 3.5941684921748 | | 2000 | 3.1864685409674 | | 1999 | 2.0749461237551 | | 1998 | -4.2991053147377 | | 1997 | 4.1614398319782 | | 1996 | 0.24573751035479 |
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