Year	constant 2015 US$
1960	303190000
1961	275270000
1962	234140000
1963	186800000
1964	141300000
1965	58220000
1966	14270000
1967	19420000
1968	44670000
1969	50250000
1970	28050000
1971	19060000
1972	39110000
1973	65440000
1974	56130000
1975	5570000
1976	31840000
1977	25240000
1978	17130000
1979	9000000
1980	28390000
1981	10540000
1982	248290000
1983	12700000
1984	11770000
1985	13440000
1986	22570000
1987	10170000
1988	8590000
1989	15750000
1990	11110000
1991	9940000
1992	4110000
1993	3730000
1994	4970000
1995	6450000
1996	4270000
1997	5010000
1998	7100000
1999	6080000
2000	21240000
2001	10310000
2002	9750000
2003	9200000
2004	13290000
2005	24620000
2006	41990000
2007	18680000
2008	66840000
2009	36190000
2010	7640000
2011	600220000
2012	82210000
2013	113160000
2014	185720000
2015	155770000
2016	179490000
2017	421260000