Year Average 1990 = 100 1975-12-31 474.81 1976-12-31 470.88 1977-12-31 461.22 1978-12-31 407.03 1979-12-31 370.12 1980-12-31 334.82 1981-12-31 321.2 1982-12-31 291.05 1983-12-31 237.94 1984-12-31 210.75 1985-12-31 149.24 1986-12-31 131.36 1987-12-31 120.53 1988-12-31 114.58 1989-12-31 106.59 1990-12-31 94.79 1991-12-31 85.63 1992-12-31 78.19 1993-12-31 72.69 1994-12-31 68.91 1995-12-31 66.44 1996-12-31 66.29 1997-12-31 65.17 1998-12-31 61.98 1999-12-31 59.48 2000-12-31 57.55 2001-12-31 57.5