Year	US Dollars
1970	103816000
1971	145537000
1972	229642000
1973	396229000
1974	528007000
1975	882648000
1976	1234274000
1977	1476400000
1978	1512806000
1979	1722579000
1980	1514019000
1981	1135599000
1982	1000630000
1983	914895000
1984	919428000
1985	1206161000
1986	1943577000
1987	2618911000
1988	2844960000
1989	3350490000
1990	3982878000
1991	4222973000
1992	3849992000
1993	3861395000
1994	4171608000
1995	4360765000
1996	4311298000
1997	4280153000
1998	4428251000
1999	4004025000
2000	3920057000
2001	3436503000
2002	3491991000
2003	3770531000
2004	4083319000
2005	3896909000
2006	4203328000
2007	4859772000
2008	2152837000
2009	2324465000
2010	2523865000
2011	2798393000
2012	2869665000
2013	4323199000
2014	4256795000
2015	5057389000
2016	5076812000