| Year | Value | | 2021 | 5.3684546911205 | | 2020 | -2.7405352565493 | | 2019 | 3.0141768638088 | | 2018 | 3.6917902658785 | | 2017 | 3.8686647124657 | | 2016 | 7.2376868947066 | | 2015 | 6.5195632549946 | | 2014 | 3.8790619457687 | | 2013 | 5.7143468506511 | | 2012 | 5.5371938109821 | | 2011 | 5.181713332964 | | 2010 | 2.3487661603008 | | 2009 | 23.995196023466 | | 2008 | -1.4800986197604 | | 2007 | -653.52641289033 | | 2006 | -51.539537600886 | | 2005 | 234.73908992344 | | 2004 | -88.266846653445 | | 2003 | -450.90674098563 | | 2002 | -129.35891406818 | | 2001 | 31.391901612476 | | 2000 | 177.94508463265 | | 1999 | -368.05379246266 | | 1998 | -93.040407405184 | | 1997 | -11.269113626529 | | 1996 | -40.641881041352 | | 1995 | 5.3527161089558 | | 1994 | 29.902699844951 | | 1993 | 40.755159974143 | | 1992 | 13.561570809344 | | 1991 | -20.079144325872 | | 1990 | 58.177199524768 | | 1989 | 13.526755815614 | | 1988 | -60.5511746088 | | 1987 | -15.931470029838 | | 1986 | -3.5746597685726 | | 1985 | 40.864749424946 | | 1984 | 46.57045873581 | | 1983 | 226.58299299831 | | 1982 | 7.077276315799 | | 1981 | 16.61168129465 | | 1980 | 25.801731798654 | | 1979 | 3.1186868668176 | | 1978 | 9.3297241434732 | | 1977 | 10.493847948466 | | 1976 | 7.9196713854211 | | 1975 | 3.9985504752246 | | 1974 | 8.525323154088 | | 1973 | 10.046466028656 | | 1972 | 5.8400072166658 | | 1971 | 8.7877768326009 |
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