Year	constant 2015 US$
1960	39770000
1961	32270000
1962	11470000
1963	37490000
1964	1920000
1965	32120000
1966	15740000
1967	17320000
1968	8370000
1969	7160000
1970	9540000
1971	23200000
1972	16620000
1973	3290000
1974	3460000
1975	-5060000
1976	9230000
1977	6940000
1978	6050000
1979	27730000
1980	23460000
1981	21280000
1982	18510000
1983	20600000
1984	32820000
1985	53690000
1986	40550000
1987	36160000
1988	35410000
1989	63120000
1990	53190000
1991	48840000
1992	-45900000
1993	38070000
1994	32140000
1995	17990000
1996	13580000
1997	10260000
1998	8220000
1999	3910000
2000	4870000
2001	4160000
2002	4880000
2003	5840000
2004	7800000