Year US Dollars adjusted for inflation) 1970 30940 1971 31190 1972 32530 1973 34240 1974 35590 1975 34680 1976 40130 1977 43230 1978 44750 1979 52920 1980 47120 1981 36020 1982 35270 1983 34920 1984 34000 1985 32390 1986 30480 1987 30080 1988 29450 1989 28260 1990 28170 1991 28460 1992 27340 1993 26700 1994 26440 1995 26250 1996 26760 1997 26860 1998 26750 1999 24970 2000 25110 2001 25320 2002 25590 2003 26240