Year US Dollars adjusted for inflation) 1970 7005 1971 7438 1972 8037 1973 8683 1974 9390 1975 10150 1976 10970 1977 11890 1978 12770 1979 13610 1980 14290 1981 14960 1982 15590 1983 16030 1984 16800 1985 16670 1986 17250 1987 19150 1988 20110 1989 20730 1990 21870 1991 21620 1992 23160 1993 23870 1994 24460 1995 25260 1996 25320 1997 24940 1998 23840 1999 22980 2000 24220 2001 24680 2002 26850 2003 30420 2004 37960