| Year | Value | | 2013 | -120.62967397686 | | 2012 | -148.58987577748 | | 2011 | -178.43297181696 | | 2010 | -144.77025071868 | | 2009 | -87.476070717369 | | 2008 | -103.8078815446 | | 2007 | -139.34333397332 | | 2006 | -165.62924117895 | | 2005 | -210.39879600047 | | 2004 | -233.63865535213 | | 2003 | -286.65080828173 | | 2002 | -335.87781439884 | | 2001 | -319.81741801656 | | 2000 | -364.10084471947 | | 1999 | -341.59374391938 | | 1998 | -370.22398686882 | | 1997 | -393.18670814292 | | 1996 | -400.57538154566 | | 1995 | -405.84853727311 | | 1994 | -461.3099295276 | | 1993 | -278.8117178077 | | 1992 | -167.27756323031 | | 1991 | -237.41601413342 | | 1990 | -273.3503113656 | | 1989 | -271.48153860416 | | 1988 | -238.51336825051 | | 1987 | 54.927524474133 | | 1986 | 77.332426429171 | | 1985 | 96.041301154443 | | 1984 | 95.986425129951 | | 1983 | 95.880043553606 | | 1982 | 95.729225166294 | | 1981 | 95.087035467282 | | 1980 | 95.268441151935 | | 1979 | 93.994772195933 | | 1978 | 94.041544507517 | | 1977 | 93.865160669135 | | 1976 | 93.525362939285 | | 1975 | 92.327630746788 | | 1974 | 93.546671871266 | | 1973 | 94.833527877912 | | 1972 | 91.301813943323 | | 1971 | 93.374813001496 |
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