Year	constant 2015 US$
1960	1300000
1961	1130000
1962	129720000
1963	296810000
1964	141140000
1965	467540000
1966	303640000
1967	340100000
1968	366130000
1969	236000000
1970	222150000
1971	154740000
1972	135240000
1973	108720000
1974	80040000
1975	103790000
1976	109150000
1977	103570000
1978	134770000
1979	194310000
1980	280730000
1981	235360000
1982	301830000
1983	222420000
1984	400460000
1985	431430000
1986	174490000
1987	219590000
1988	186500000
1989	228270000
1990	144830000
1991	91960000
1992	78760000
1993	-23130000
1994	78010000
1995	113600000
1996	114390000
1997	87060000
1998	152980000
1999	239350000
2000	69620000
2001	138840000
2002	186620000
2003	75000000
2004	85330000
2005	81070000
2006	67750000
2007	114980000
2008	140750000
2009	107800000
2010	163270000
2011	193280000
2012	241050000
2013	133530000
2014	148560000
2015	280310000
2016	176700000
2017	114840000