| Year | Value | | 2021 | 1.6744574471316 | | 2020 | 0.73319144129103 | | 2019 | 4.6252488445855 | | 2018 | 3.7369770894033 | | 2017 | 5.0168940004489 | | 2016 | 3.8044780797511 | | 2015 | 0.59721020440439 | | 2014 | 5.4056493797757 | | 2013 | 4.4265406167966 | | 2012 | 3.0929222824231 | | 2011 | 3.9541634980183 | | 2010 | 0.45131530924637 | | 2009 | -13.063352205554 | | 2008 | 5.0008177737851 | | 2007 | 9.3866771208959 | | 2006 | 5.4317616397326 | | 2005 | 9.8299794960677 | | 2004 | 11.139078999419 | | 2003 | 9.4155046093964 | | 2002 | 8.5766180327592 | | 2001 | 7.7043530411689 | | 2000 | 6.8418651724297 | | 1999 | 0.30047674258273 | | 1998 | 7.7116716158281 | | 1997 | 11.567180656363 | | 1996 | 11.452136892706 |
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