Year	constant 2015 US$
1960	330000
1961	9580000
1962	20150000
1963	14530000
1964	88430000
1965	65920000
1966	145700000
1967	84270000
1968	146400000
1969	77000000
1970	46230000
1971	81850000
1972	67190000
1973	133960000
1974	390290000
1975	291140000
1976	692090000
1977	550630000
1978	648990000
1979	412730000
1980	380760000
1981	509380000
1982	438870000
1983	422120000
1984	419480000
1985	498440000
1986	445970000
1987	324760000
1988	288160000
1989	402190000
1990	329590000
1991	293040000
1992	249900000
1993	422810000
1994	325520000
1995	244700000
1996	310770000
1997	297410000
1998	210730000
1999	283350000
2000	307540000
2001	407450000
2002	503550000
2003	306490000
2004	208450000
2005	199640000
2006	221660000
2007	325130000
2008	408040000
2009	342220000
2010	343230000
2011	328040000
2012	368760000
2013	262320000
2014	232960000
2015	319810000
2016	294080000
2017	279590000