Year	constant 2015 US$
1974	8220000
1975	5860000
1976	8060000
1977	5470000
1978	10010000
1979	1880000
1980	3060000
1981	2230000
1982	1290000
1983	850000
1984	820000
1985	150000
1986	3780000
1987	3530000
1988	18380000
1989	2000000
1990	4040000
1991	-340000
1992	130000
1993	-430000
1994	-1170000
1995	-550000
1996	-2140000
1997	-4590000
1998	380000
1999	4090000
2000	-5310000
2001	-1180000
2002	-2550000
2003	-1670000
2004	480000