Year	constant 2015 US$
1960	10460000
1961	9220000
1962	4350000
1963	5620000
1964	8000000
1965	12360000
1966	7030000
1967	16800000
1968	20360000
1969	9990000
1970	28610000
1971	49930000
1972	51150000
1973	43880000
1974	42180000
1975	30930000
1976	32210000
1977	41530000
1978	48150000
1979	59390000
1980	43270000
1981	36250000
1982	41310000
1983	36160000
1984	36910000
1985	57850000
1986	57240000
1987	41040000
1988	32030000
1989	32120000
1990	51290000
1991	30830000
1992	26230000
1993	26690000
1994	17190000
1995	13450000
1996	22780000
1997	22090000
1998	32200000
1999	17010000
2000	32710000
2001	17810000
2002	78530000
2003	10920000
2004	11270000
2005	18010000
2006	13890000
2007	5950000
2008	6510000
2009	19730000
2010	48240000
2011	19270000
2012	31000000
2013	23880000
2014	10630000
2015	6810000
2016	5760000
2017	18750000