Year	US Dollars
1970	345218000
1971	410052000
1972	676590000
1973	1046503000
1974	1538496000
1975	2038616000
1976	2918442000
1977	3661972000
1978	4491698000
1979	4527131000
1980	4770690000
1981	5090777000
1982	5078793000
1983	5335732000
1984	5289769000
1985	6171264000
1986	7190747000
1987	8757682000
1988	8562157000
1989	9251497000
1990	10258588000
1991	10840413000
1992	11004125000
1993	11273324000
1994	12321601000
1995	13239366000
1996	12830258000
1997	12337528000
1998	13202856000
1999	12166588000
2000	11815383000
2001	11623275000
2002	10062785000
2003	11444750000
2004	11535208000
2005	10694719000
2006	11336903000
2007	12469708000
2008	12306290000
2009	13102291000
2010	6145384000
2011	5507620000
2012	5623972000
2013	6177066000
2014	5522884000
2015	5388168000
2016	5076936000