| Year | Value | | 2022 | 0.36450517984917 | | 2021 | 0.20210414455853 | | 2020 | 0.028168132639065 | | 2019 | 0.010952131373941 | | 2018 | 0.070427497805042 | | 2017 | -1.0605345960762 | | 2016 | -1.0524709796827 | | 2015 | 0.15186963609296 | | 2014 | 0.21054418830446 | | 2013 | 0.31279157082908 | | 2012 | 0.36177587733559 | | 2011 | 0.86361649582349 | | 2010 | 0.78311810436358 | | 2009 | 0.55458513987987 | | 2008 | 0.59157677460615 | | 2007 | 0.564095738183 | | 2006 | 0.57353064103444 | | 2005 | 0.6474133986679 | | 2004 | 0.65321131014515 | | 2003 | 0.65432713630377 | | 2002 | 0.65063698302582 | | 2001 | 1.0793352165173 | | 2000 | 0.89020877361416 | | 1999 | 0.55961136976709 | | 1998 | 0.73452240649862 | | 1997 | 0.61015227509119 | | 1996 | 0.63900113155912 | | 1995 | 0.7155725694237 | | 1994 | 0.69356617361355 | | 1993 | 0.53614868230302 | | 1992 | 0.72439440697037 | | 1991 | 0.51543456995343 | | 1990 | 0.82087676496518 | | 1989 | 0.84309473010737 | | 1988 | 0.85717761235004 | | 1987 | 0.81055021094964 | | 1986 | 0.84704741664358 | | 1985 | 0.83833143355917 | | 1984 | 0.87759679605571 | | 1983 | 0.86372294648436 | | 1982 | 0.7221816199964 | | 1981 | 0.6926750261781 | | 1980 | 1.6041645739169 | | 1979 | 0.37243990909823 | | 1978 | 0.37383221106072 | | 1977 | 0.37523496185504 | | 1976 | 0.37664827954769 | | 1975 | 0.75188324140273 | | 1974 | 0.74627212015896 | | 1973 | 0.74074412778619 | | 1972 | 0.73529743052588 | | 1971 | 0.72993024816115 | | 1970 | 1.8349138668197 | | 1969 | 1.8692133012153 | | 1968 | 1.9048194970694 | | 1967 | 1.9418085857101 | | 1966 | 1.7804624633507 | | 1965 | 2.4243611609993 | | 1964 | 2.4845998586531 | | 1963 | 2.3330856762695 | | 1962 | 2.3888215174696 | | 1961 | 2.4472856518726 |
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