| Year | Value | | 2021 | 3.0230014506618 | | 2020 | 1.9380207188992 | | 2019 | 5.5685126923769 | | 2018 | 8.4583876435504 | | 2017 | 4.2788626259662 | | 2016 | 7.0003454804505 | | 2015 | 4.7423017781059 | | 2014 | 12.779460556614 | | 2013 | 4.4409844906525 | | 2012 | -1.6917147901742 | | 2011 | 4.646488556824 | | 2010 | 6.1099913930052 | | 2009 | 17.502062040525 | | 2008 | 5.6730447822916 | | 2007 | 5.0893418241549 | | 2006 | 11.825483092206 | | 2005 | 7.7154655905719 | | 2004 | 15.302459860772 | | 2003 | -2.9104045935126 | | 2002 | 5.0035160030348 | | 2001 | 0.96120283970053 | | 2000 | -2.2281057483464 | | 1999 | 13.014140721556 | | 1998 | 0.8901246574472 | | 1997 | 10.381142824312 | | 1996 | 6.2061325635673 | | 1995 | 18.175100142924 | | 1994 | 11.562529150791 | | 1993 | 27.055427288485 | | 1992 | -7.0100875113404 | | 1991 | -4.8776605410613 | | 1990 | -4.723298928849 | | 1989 | 0.60908951276302 | | 1988 | 9.0184274771055 | | 1987 | 10.070367441275 | | 1986 | -5.3371501911538 | | 1985 | 0.88909864361447 | | 1984 | 14.241672917261 | | 1983 | 31.087506118997 |
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