| Year | Value | | 2021 | 5.5727640535438 | | 2020 | -6.5996335715391 | | 2019 | 2.9645404707117 | | 2018 | 1.0222425742806 | | 2017 | 1.2598996849185 | | 2016 | 1.6411219212963 | | 2015 | 2.3761439900635 | | 2014 | 1.6429685068292 | | 2013 | 1.0090747213192 | | 2012 | 3.2571132369609 | | 2011 | -1.3418159154946 | | 2010 | 1.4128333327445 | | 2009 | -1.4115109089658 | | 2008 | -1.3456926053632 | | 2007 | 3.5749895605311 | | 2006 | 1.7638637427917 | | 2005 | 1.3264466017651 | | 2004 | 2.3705678836486 | | 2003 | 0.32243650858348 | | 2002 | 1.8837478703062 | | 2001 | 0.0014526418411265 | | 2000 | 2.7002217733541 | | 1999 | 2.3901650954596 | | 1998 | 2.0053390875234 | | 1997 | 3.5548134953235 | | 1996 | 0.45605665190067 | | 1995 | 1.5926466239202 | | 1994 | 3.9010530630122 | | 1993 | 0.69023562502126 | | 1992 | 2.4116620082741 | | 1991 | 2.1284122017593 | | 1990 | 2.820191918394 | | 1989 | 3.5849669343593 | | 1988 | 6.0101104157171 | | 1987 | 3.1720729466319 | | 1986 | 4.8070539999048 | | 1985 | 2.8814139912415 | | 1984 | 3.1824164738967 | | 1983 | 0.82534458766976 | | 1982 | 0.15224966336919 | | 1981 | -2.619021983642 | | 1980 | 0.59364399782187 | | 1979 | 1.9002403777023 | | 1978 | 2.8608344013793 | | 1977 | 0.074239312325602 | | 1976 | 5.7453305515808 | | 1975 | -1.1981800001026 | | 1974 | 1.6760137611332 | | 1973 | 6.9092633185285 | | 1972 | 6.4234305698808 | | 1971 | 3.3417792045648 |
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