Year	constant 2015 US$
1960	51120000
1961	-2640000
1962	-63990000
1963	-16020000
1964	-2880000
1965	2540000
1966	2300000
1967	3150000
1968	3300000
1969	8560000
1970	8700000
1971	10670000
1972	11200000
1973	11930000
1974	14260000
1975	10730000
1976	6140000
1977	20390000
1978	15860000
1979	24630000
1980	27590000
1981	57210000
1982	108360000
1983	94890000
1984	79810000
1985	63760000
1986	52110000
1987	33860000
1988	26190000
1989	19890000
1990	18850000
1991	17020000
1992	52610000
1993	31420000
1994	17290000
1995	15830000
1996	13510000
1997	3120000
1998	19080000
1999	23670000
2000	24110000
2001	16000000
2002	20370000
2003	15440000
2004	22250000
2005	25370000
2006	24420000
2007	-143320000