Year	constant 2015 US$
1961	-1200000
1962	-17980000
1963	-7120000
1964	-6010000
1965	-8630000
1966	-9430000
1967	-9410000
1968	80000
1969	2140000
1970	2060000
1971	2840000
1972	2940000
1973	1760000
1974	1490000
1975	1200000
1976	660000
1977	1490000
1978	2270000
1979	2700000
1980	20870000
1981	21560000
1982	13770000
1983	12350000
1984	11420000
1985	10690000
1986	9310000
1987	5190000
1988	7980000
1989	7160000
1990	17860000
1991	15820000
1992	8260000
1993	2500000
1994	5430000
1995	4610000