Year	US Dollars
1970	0
1971	0
1972	0
1973	0
1974	0
1975	0
1976	0
1977	0
1978	0
1979	0
1980	0
1981	5798016000
1982	8359970000
1983	9611696000
1984	12088825000
1985	16699019000
1986	23719324000
1987	35339512000
1988	42438956000
1989	44932462000
1990	55301411000
1991	60259176000
1992	72427953000
1993	85927702000
1994	100456856000
1995	118089788000
1996	128817086000
1997	146696958000
1998	144006763000
1999	148585022000
2000	145666447000
2001	184075276000
2002	185214337000
2003	206555683000
2004	245763235000
2005	283309820000
2006	323134636000
2007	373457376000
2008	380164840000
2009	447662212000
2010	734465434000
2011	1044355045000
2012	1138247396000
2013	1471617817000
2014	1770542954000
2015	1325957105000
2016	1429467967000