Year US Dollars adjusted for inflation) 1970 1731 1971 1748 1972 2120 1973 2119 1974 2148 1975 2263 1976 2270 1977 2121 1978 2205 1979 2121 1980 2121 1981 2298 1982 2423 1983 2529 1984 2556 1985 2549 1986 2617 1987 2326 1988 2096 1989 1907 1990 1751 1991 1837 1992 1447 1993 1137 1994 1022 1995 920.7 1996 939.7 1997 1029 1998 1047 1999 880.6 2000 478.1 2001 418.2 2002 525.9 2003 588.1 2004 580.8