Year	constant 2015 US$
1960	17300000
1961	25780000
1962	46150000
1963	35620000
1964	10320000
1965	15970000
1966	18640000
1967	42960000
1968	43820000
1969	51880000
1970	41450000
1971	31600000
1972	46080000
1973	24340000
1974	28710000
1975	33160000
1976	45410000
1977	32900000
1978	53820000
1979	53620000
1980	29760000
1981	23980000
1982	27310000
1983	32980000
1984	32530000
1985	46550000
1986	47360000
1987	42950000
1988	41860000
1989	46970000
1990	45530000
1991	31780000
1992	35620000
1993	43760000
1994	43310000
1995	23390000
1996	26920000
1997	17900000
1998	19530000
1999	57420000
2000	22860000
2001	32420000
2002	30380000
2003	15560000
2004	8200000
2005	12360000
2006	8370000
2007	21430000
2008	21210000
2009	24940000
2010	22530000
2011	19060000
2012	23650000
2013	47220000
2014	33170000
2015	28330000
2016	34960000
2017	33450000