| Year | Value | | 2015 | -581.34657349589 | | 2014 | -582.89933937648 | | 2013 | -494.81574777482 | | 2012 | -584.36291345596 | | 2011 | -611.50128022099 | | 2010 | -512.23148212626 | | 2009 | -594.18678652261 | | 2008 | -588.73625131327 | | 2007 | -680.48428682988 | | 2006 | -693.01554477093 | | 2005 | -736.37182703246 | | 2004 | -764.51817625463 | | 2003 | -768.20769398621 | | 2002 | -843.48187881192 | | 2001 | -744.03694026827 | | 2000 | -771.48364612918 | | 1999 | -696.52984463688 | | 1998 | -719.75543681915 | | 1997 | -784.42263891977 | | 1996 | -812.01697514079 | | 1995 | -687.17184194852 | | 1994 | -639.81235271252 | | 1993 | -559.84652351194 | | 1992 | -565.31200507426 | | 1991 | -504.26274267173 | | 1990 | -467.1067969276 | | 1989 | -437.02150950231 | | 1988 | -369.27095839338 | | 1987 | -310.27593168511 | | 1986 | -258.45626978784 | | 1985 | -263.91894984454 | | 1984 | -260.85121153204 | | 1983 | -248.25060304132 | | 1982 | -216.65104419142 | | 1981 | -206.63977095737 | | 1980 | -200.15216138643 | | 1979 | -152.88254281025 | | 1978 | -109.06582521722 | | 1977 | -42.097554301509 | | 1976 | -36.741738876639 | | 1975 | -10.484692991963 | | 1974 | 39.889189706827 | | 1973 | 43.570686359107 | | 1972 | 44.393702186312 | | 1971 | 54.744923369441 | | 1970 | 60.032060764767 | | 1969 | 57.655399072724 | | 1968 | 53.579293088853 | | 1967 | 54.17837007808 | | 1966 | 55.962959627394 | | 1965 | 51.867710012608 | | 1964 | 51.936730209085 | | 1963 | 53.939699088896 | | 1962 | 51.800366345987 | | 1961 | 54.91717075249 | | 1960 | 56.541684513866 |
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