Year	constant 2015 US$
1960	1606800000
1961	1452290000
1962	1477180000
1963	1667230000
1964	1078730000
1965	1514880000
1966	1467240000
1967	1643750000
1968	1475320000
1969	2052960000
1970	1576030000
1971	1807870000
1972	1787460000
1973	1233160000
1974	993530000
1975	888930000
1976	732060000
1977	725230000
1978	419280000
1979	314300000
1980	307760000
1981	696800000
1982	82330000
1983	26120000
1984	-62570000
1985	-6480000
1986	-26490000
1987	10810000
1988	2850000
1989	60770000
1990	53150000
1991	55610000
1992	-21910000
1993	-50880000
1994	-114570000
1995	24370000
1996	-154910000
1997	-169220000
1998	-60480000
1999	-57630000