Year	constant 2015 US$
1960	1420000
1961	21010000
1962	76250000
1963	168630000
1964	90680000
1965	149630000
1966	88600000
1967	49370000
1968	37450000
1969	83400000
1970	65520000
1971	51480000
1972	23380000
1973	53630000
1974	77340000
1975	86000000
1976	34950000
1977	67810000
1978	165370000
1979	134140000
1980	194130000
1981	248590000
1982	269530000
1983	160970000
1984	296890000
1985	274130000
1986	331160000
1987	359240000
1988	389080000
1989	574430000
1990	399460000
1991	510460000
1992	563520000
1993	532420000
1994	452780000
1995	462950000
1996	353260000
1997	493590000
1998	460180000
1999	307760000
2000	208120000
2001	408030000
2002	344410000
2003	297870000
2004	299280000
2005	208920000
2006	181780000
2007	245070000
2008	316320000
2009	196170000
2010	203410000
2011	176020000
2012	571280000
2013	418450000
2014	500250000
2015	540560000
2016	555430000
2017	448890000