Year	constant 2015 US$
1960	108530000
1961	-6360000
1962	11750000
1963	79740000
1964	31780000
1965	2610000
1966	37240000
1967	37340000
1968	308800000
1969	111980000
1970	78930000
1971	58880000
1972	109920000
1973	87470000
1974	44020000
1975	41490000
1976	43840000
1977	52140000
1978	25210000
1979	32270000
1980	20300000
1981	16050000
1982	9380000
1983	7230000
1984	11330000
1985	14890000
1986	50300000
1987	27580000
1988	64340000
1989	58810000
1990	70350000
1991	63000000
1992	82760000
1993	148110000
1994	94980000
1995	74720000
1996	39710000
1997	41490000
1998	31160000
1999	28030000
2000	24480000
2001	21810000
2002	19730000
2003	19870000
2004	24960000
2005	17870000
2006	23980000
2007	33660000
2008	28430000
2009	45230000
2010	41840000
2011	16250000
2012	15710000
2013	32110000
2014	79130000
2015	23190000
2016	18250000
2017	39690000