| Year | Value | | 2022 | 5.3437026489544 | | 2021 | 2.9207347759295 | | 2020 | 2.9402951426397 | | 2019 | 1.9425750083311 | | 2018 | 2.4590851538015 | | 2017 | 2.9126355737148 | | 2016 | 3.0191397513913 | | 2015 | 1.2239319551112 | | 2014 | 3.8556886142421 | | 2013 | 2.9416250954735 | | 2012 | 2.9343160929395 | | 2011 | 5.4784474961745 | | 2010 | 3.9963952810722 | | 2009 | -1.2417175418964 | | 2008 | 24.096851930605 | | 2007 | 8.7088277056805 | | 2006 | 5.8106855046431 | | 2005 | 6.6152591200159 | | 2004 | 4.3193367743479 | | 2003 | 0.94174611779921 | | 2002 | 0.21146656802261 | | 2001 | 0.60064830012369 | | 2000 | 0.79199252947357 | | 1999 | 4.0082070208878 | | 1998 | 14.806503543776 | | 1997 | 7.9602139777746 | | 1996 | 7.150861408728 | | 1995 | 0.79894433781188 |
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