Year	constant 2015 US$
1960	31880000
1961	37910000
1962	49980000
1963	104790000
1964	67280000
1965	108520000
1966	104860000
1967	113970000
1968	161550000
1969	237490000
1970	235830000
1971	248070000
1972	255290000
1973	278160000
1974	292440000
1975	289390000
1976	301630000
1977	290440000
1978	299320000
1979	305410000
1980	273660000
1981	312320000
1982	350670000
1983	279030000
1984	373450000
1985	310870000
1986	438250000
1987	339240000
1988	271360000
1989	274650000
1990	101570000
1991	36670000
1992	9060000
1993	134090000
1994	3510000
1995	-720000
1996	-1370000
1997	880000
1998	260000
1999	150000