| Year | Value | | 2023 | 8.7854304984908 | | 2022 | 13.852259014427 | | 2021 | 6.6502991270878 | | 2020 | 2.7598094700813 | | 2019 | 2.6105718279922 | | 2018 | 2.26854690374 | | 2017 | 12.935918418734 | | 2016 | 12.443374858437 | | 2015 | 4.0276857374273 | | 2014 | 1.3734418153318 | | 2013 | 2.4157174527942 | | 2012 | 1.066213397203 | | 2011 | 7.8583333333334 | | 2010 | 5.7268722466961 | | 2009 | 1.4570483597032 | | 2008 | 20.849087177271 | | 2007 | 16.699754961824 | | 2006 | 8.3289248286321 | | 2005 | 9.6795073191706 | | 2004 | 6.7089304279778 | | 2003 | 2.2338649296705 | | 2002 | 2.7711647199827 | | 2001 | 1.5471959015228 | | 2000 | 1.8050030370436 | | 1999 | -8.5251700053606 | | 1998 | 0.77269788603317 | | 1997 | 3.6743480968473 | | 1996 | 19.79480280619 | | 1995 | 411.75964177727 | | 1994 | 1,662.215948759 | | 1993 | 1,128.000024294 | | 1992 | -10.63009715762 |
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