| Year | Value | | 2021 | -1.5974461696674 | | 2020 | -7.3905091449533 | | 2019 | 0.82408562201239 | | 2018 | 0.35939004959549 | | 2017 | 2.3378633885636 | | 2016 | 1.2630003093485 | | 2015 | 6.7715916521725 | | 2014 | 7.5803572789293 | | 2013 | 10.190777952049 | | 2012 | 5.2367789557545 | | 2011 | 6.7120630754142 | | 2010 | 3.3732214519867 | | 2009 | 0.62796428392437 | | 2008 | 10.205376329244 | | 2007 | -2.1052707668493 | | 2006 | 11.935063495004 | | 2005 | 0.39818489178731 | | 2004 | 7.1253960874143 | | 2003 | 2.070714584805 | | 2002 | 6.9560511081529 | | 2001 | 1.818568524777 | | 2000 | 9.1617978413951 | | 1999 | 0.47538215038048 | | 1998 | 4.1413672912942 | | 1997 | 2.406491261494 | | 1996 | 5.9062436632805 | | 1995 | 3.4772610455805 | | 1994 | 5.7139188497271 | | 1993 | 2.9735745605892 | | 1992 | 2.4652028309473 | | 1991 | 14.907576010598 |
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