| Year | Value | | 2021 | 6.3848201124544 | | 2020 | -2.2777109905461 | | 2019 | 3.3569886357683 | | 2018 | 3.5891036351116 | | 2017 | 5.5573627220999 | | 2016 | 5.0502364370623 | | 2015 | 4.2276873591524 | | 2014 | 5.0162324338186 | | 2013 | 4.4455386902649 | | 2012 | 5.7267994765624 | | 2011 | 4.904154766387 | | 2010 | 7.8624745553505 | | 2009 | 4.5397391532424 | | 2008 | 4.2753086672449 | | 2007 | 14.922059041006 | | 2006 | 11.177176902984 | | 2005 | 6.8902965481602 | | 2004 | 12.376467472859 | | 2003 | 0.37910416070804 | | 2002 | 12.417888731667 | | 2001 | 3.5142338446601 | | 2000 | 3.1714759779781 | | 1999 | 2.0104532888022 | | 1998 | -3.7539991466526 | | 1997 | 4.2424198396242 | | 1996 | 0.032869350358538 |
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