| Year | Value | | 2022 | 14.290235430336 | | 2021 | 3.6535328721421 | | 2020 | 1.8844399378199 | | 2019 | -3.2333893398333 | | 2018 | 1.9559430267252 | | 2017 | 1.4829989716132 | | 2016 | 0.4410414480589 | | 2015 | 0.72483898107052 | | 2014 | 0.25808951753538 | | 2013 | 0.53373850709054 | | 2012 | 3.818152402524 | | 2011 | 2.7597672485452 | | 2010 | 0.76423073467676 | | 2009 | 2.6081766636832 | | 2008 | 10.659797899742 | | 2007 | 0.23062730627304 | | 2006 | 2.3331085637222 | | 2005 | 6.4150401836968 | | 2004 | 0.40022870211545 | | 2003 | 2.0345657405382 | | 2002 | 2.1756948066461 | | 2001 | 5.0074329082237 | | 2000 | 0.3042121684868 | | 1999 | -1.0726136275953 | | 1998 | 5.0843334414532 | | 1997 | 2.3186906217669 | | 1996 | 6.0978043912174 | | 1995 | 7.4588449782832 | | 1994 | 25.177876224996 | | 1993 | 0.55345572354192 | | 1992 | -1.9911358073689 | | 1991 | 2.1626005271342 | | 1990 | 0.50430338891891 | | 1989 | 0.48179871520333 | | 1988 | 4.2556160178594 | | 1987 | -2.681784235116 | | 1986 | -2.6117429247678 | | 1985 | 6.9060578214047 | | 1984 | 4.8469576818608 | | 1983 | 8.1537627742043 | | 1982 | 12.059765208134 | | 1981 | 7.5557056044094 | | 1980 | 12.20263649683 | | 1979 | 14.99346595036 | | 1978 | 8.2691400721405 | | 1977 | 29.986104299714 | | 1976 | -8.4007187782054 | | 1975 | 18.756946605863 | | 1974 | 8.7196094542842 | | 1973 | 7.603890362543 | | 1972 | -2.9233565586796 | | 1971 | 2.0612181799523 | | 1970 | 1.7726033145134 | | 1969 | 9.6555293576212 | | 1968 | 0.28671368777001 | | 1967 | -4.3337539085691 | | 1966 | 2.3641060198334 | | 1965 | 0.7302525226614 | | 1964 | 1.84512319775 | | 1963 | 5.574202829151 | | 1962 | 1.6759095614018 | | 1961 | 18.562138728108 | | 1960 | 7.7881619937688 |
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