Year	constant 2015 US$
1961	740000
1962	4790000
1963	77510000
1964	81630000
1965	94800000
1966	56590000
1967	11390000
1968	51990000
1969	48170000
1970	35360000
1971	35490000
1972	22650000
1973	18000000
1974	23100000
1975	18950000
1976	16670000
1977	16880000
1978	12250000
1979	9930000
1980	8270000
1981	-2780000
1982	12510000
1983	12480000
1984	10880000
1985	17650000
1986	36850000
1987	54310000
1988	13670000
1989	8750000
1990	24950000
1991	-2930000
1992	10220000
1993	2200000
1994	27420000
1995	29690000
1996	19710000
1997	42840000
1998	18120000
1999	34840000
2000	-3980000
2001	-4350000
2002	-13350000
2003	-3740000
2004	-1820000
2005	-1860000
2006	13550000
2007	18840000
2008	7900000
2009	6300000
2010	4130000