| Year | Value | | 2024 | 0.18067872342205 | | 2023 | 0.18035286408109 | | 2022 | 0.13505150890655 | | 2021 | 0.050597330664828 | | 2020 | 0.03371733664986 | | 2019 | 0.089857357500723 | | 2018 | 0.011227755022181 | | 2017 | 0.084248369160733 | | 2016 | 0.15182616012887 | | 2015 | 0.30999038491246 | | 2014 | 0.37892758062887 | | 2013 | 0.66077669618437 | | 2012 | -1.7465499903229 | | 2011 | -1.7437520301458 | | 2010 | -1.6871441825604 | | 2009 | -1.5907859720735 | | 2008 | -1.5296166260928 | | 2007 | -1.4963642103685 | | 2006 | -1.1468713953581 | | 2005 | 0.005045535963131 | | 2004 | 0.81562801763724 | | 2003 | 0.79669488350281 | | 2002 | 0.77725265827153 | | 2001 | 0.90319845762367 | | 2000 | 1.454895801267 | | 1999 | 2.0147642100314 | | 1998 | 2.2713359044793 | | 1997 | 2.5391442975671 | | 1996 | 2.6343742713812 | | 1995 | 2.5027068049112 | | 1994 | 2.4019017204961 | | 1993 | 2.3671572826873 | | 1992 | 2.3733038105184 | | 1991 | 2.2998454788501 | | 1990 | 2.0792697173697 | | 1989 | 2.0277815456205 | | 1988 | 2.1464642707969 | | 1987 | 2.1864189952794 | | 1986 | 2.4250611029041 | | 1985 | 2.5977408949635 | | 1984 | 2.5131338193297 | | 1983 | 2.4281348562682 | | 1982 | 2.3271690956592 | | 1981 | 1.0618994933276 | | 1980 | 0.53641220949168 | | 1979 | 0.83142102217059 | | 1978 | 0.68095596598951 | | 1977 | 0.58114242288087 | | 1976 | 0.45143227973501 | | 1975 | 0.25254531613738 |
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