Year US Dollars adjusted for inflation) 1970 14960 1971 17510 1972 20950 1973 26600 1974 32130 1975 30490 1976 31520 1977 30270 1978 28630 1979 30960 1980 30970 1981 30680 1982 24660 1983 19960 1984 18240 1985 17380 1986 17260 1987 16140 1988 16570 1989 16050 1990 17420 1991 18570 1992 18680 1993 17650 1994 17400 1995 16920 1996 17000 1997 16760 1998 16460 1999 15550 2000 15830 2001 15480 2002 14690 2003 16010