Year	constant 2015 US$
1960	117650000
1961	90250000
1962	78480000
1963	151490000
1964	166780000
1965	131720000
1966	132830000
1967	121160000
1968	138430000
1969	117810000
1970	135880000
1971	96580000
1972	78440000
1973	134420000
1974	93940000
1975	123860000
1976	111030000
1977	103280000
1978	110240000
1979	125000000
1980	36340000
1981	139110000
1982	69840000
1983	119280000
1984	30320000
1985	46290000
1986	13620000
1987	-2240000
1988	-4340000
1989	-8190000
1990	7540000
1991	30090000
1992	5540000
1993	45640000
1994	63350000
1995	13270000
1996	92240000
1997	31140000
1998	30260000
1999	35470000
2000	34030000
2001	2740000
2002	15940000