Year	constant 2015 US$
1960	6890480000
1961	7192790000
1962	6612670000
1963	6026550000
1964	5659750000
1965	4554600000
1966	4494520000
1967	3035710000
1968	3288120000
1969	3079700000
1970	4250270000
1971	4035720000
1972	4303750000
1973	9424230000
1974	15192080000
1975	19638330000
1976	19776530000
1977	21542070000
1978	18504470000
1979	19236340000
1980	20466210000
1981	20190730000
1982	17284820000
1983	14948640000
1984	14119440000
1985	15517950000
1986	12339410000
1987	11484570000
1988	8407160000
1989	8236660000
1990	18440220000
1991	16176990000
1992	10997720000
1993	9901780000
1994	9906300000
1995	6976130000
1996	7583950000
1997	7521500000
1998	8506760000
1999	7176020000
2000	6969920000
2001	7829080000
2002	7255160000
2003	11087070000
2004	13223670000
2005	32379710000
2006	18807060000
2007	18834330000
2008	21147850000
2009	13921540000
2010	11812370000
2011	12341460000
2012	13690830000
2013	20274460000
2014	19903110000
2015	20502490000
2016	27384130000
2017	29495560000