| Year | Value | | 2021 | 12.443073012433 | | 2020 | -3.6930943960699 | | 2019 | 0.75075304972776 | | 2018 | 3.7550653583942 | | 2017 | 1.9172343727987 | | 2016 | 3.5217271144147 | | 2015 | 0.40051669674519 | | 2014 | 0.71799634816658 | | 2013 | 2.0417613217321 | | 2012 | -1.0146229416574 | | 2011 | 0.52504254510941 | | 2010 | 5.4028573447047 | | 2009 | 0.80016716625626 | | 2008 | 6.336493985698 | | 2007 | 3.4657978832311 | | 2006 | 7.0912596097316 | | 2005 | 3.8039130287211 | | 2004 | 5.9974724359886 | | 2003 | 5.1747565335528 | | 2002 | 3.3338522572317 | | 2001 | 10.019666394767 | | 2000 | 11.226239221911 | | 1999 | 14.933809812075 | | 1998 | 5.4728714966253 |
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