| Year | Value | | 2004 | 2.0608208332356 | | 2003 | -8.8613495447748 | | 2002 | 0.96095737067191 | | 2001 | -1.8587435236007 | | 2000 | -7.6616182180659 | | 1999 | 1.6238514437947 | | 1998 | -1.3273481157112 | | 1997 | 6.7344213246964 | | 1996 | 12.966794493095 | | 1995 | -11.73147259667 | | 1994 | 12.124514852002 | | 1993 | 12.209132209552 | | 1992 | 7.1902168789949 | | 1991 | 14.301259029284 | | 1990 | -4.7469510870846 | | 1989 | -7.7955001620166 | | 1988 | 6.6822351585341 | | 1987 | 0.06194284608577 | | 1986 | 2.3574980396306 | | 1985 | -5.0449203532352 | | 1984 | 9.3220360864022 | | 1983 | 6.0238690189692 | | 1982 | -3.6961916511137 | | 1981 | -6.5557880958577 |
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