Year	US Dollars
1970	8345000
1971	15633000
1972	18802000
1973	32603000
1974	41034000
1975	44232000
1976	108234000
1977	172944000
1978	255343000
1979	310867000
1980	352944000
1981	392653000
1982	431286000
1983	453212000
1984	520892000
1985	621358000
1986	870922000
1987	1163999000
1988	1328066000
1989	1474077000
1990	1768539000
1991	1873131000
1992	1917267000
1993	1986718000
1994	2071422000
1995	2158262000
1996	2258223000
1997	2325961000
1998	2459335000
1999	2559998000
2000	2531033000
2001	2585719000
2002	3168467000
2003	2506301000
2004	2949487000
2005	3278601000
2006	3805627000
2007	4987665000
2008	5653262000
2009	6383405000
2010	6504790000
2011	7521585000
2012	8159215000
2013	9795565000
2014	11400236000
2015	13012454000
2016	14159855000