Year	constant 2015 US$
1960	-2470000
1961	-350000
1962	8520000
1963	4850000
1964	4120000
1965	17960000
1966	14280000
1967	51790000
1968	35250000
1969	116490000
1970	201650000
1971	197810000
1972	169600000
1973	129710000
1974	85540000
1975	45150000
1976	41810000
1977	38650000
1978	15090000
1979	11890000
1980	29900000
1981	48010000
1982	48090000
1983	33630000
1984	90360000
1985	57850000
1986	53350000
1987	36600000
1988	30960000
1989	146950000
1990	-760000
1991	9540000
1992	23380000
1993	24830000
1994	15890000
1995	14570000