Year	US Dollars
1970	0
1971	0
1972	0
1973	0
1974	0
1975	0
1976	0
1977	0
1978	0
1979	0
1980	4618943000
1981	3969212000
1982	8269751000
1983	7078087000
1984	5159731000
1985	6025227000
1986	5793966000
1987	6150724000
1988	5843050000
1989	6526858000
1990	9026182000
1991	11368429000
1992	16074663000
1993	23392441000
1994	21792479000
1995	21681653000
1996	16684173000
1997	11697339000
1998	12341636000
1999	9742307000
2000	8130251000
2001	7647084000
2002	8934508000
2003	14235372000
2004	20950355000
2005	21393523000
2006	20494229000
2007	20834060000
2008	16026647000
2009	18609982000
2010	19768743000
2011	17260285000
2012	7471977000
2013	6993578000
2014	5758232000
2015	6321580000
2016	5378273000