Year	US Dollars
1970	144132000
1971	162143000
1972	184902000
1973	208206000
1974	257138000
1975	310688000
1976	375034000
1977	555084000
1978	723509000
1979	912111000
1980	1056126000
1981	1249022000
1982	1396513000
1983	1510712000
1984	1563671000
1985	1907740000
1986	2173398000
1987	2610091000
1988	2433417000
1989	2459601000
1990	2176253000
1991	2129188000
1992	1690939000
1993	1649954000
1994	2153330000
1995	2617586000
1996	2604083000
1997	2496674000
1998	2826031000
1999	3433333000
2000	3106035000
2001	2867283000
2002	3373052000
2003	6798832000
2004	7376895000
2005	8302217000
2006	9565285000
2007	10714075000
2008	12520041000
2009	13941378000
2010	15902556000
2011	15580877000
2012	16046077000
2013	15709998000
2014	16495045000
2015	16124878000
2016	16323430000