Year	US Dollars
1970	389548000
1971	439941000
1972	480997000
1973	516416000
1974	625955000
1975	729788000
1976	875533000
1977	1189250000
1978	1406647000
1979	1682577000
1980	2081567000
1981	2372036000
1982	2598219000
1983	3002658000
1984	3184571000
1985	3573467000
1986	3762209000
1987	4012436000
1988	4072687000
1989	4159661000
1990	4484666000
1991	4599351000
1992	4716246000
1993	4957326000
1994	4366322000
1995	4532952000
1996	4414761000
1997	4309979000
1998	4473716000
1999	4794694000
2000	4617977000
2001	5212381000
2002	6574924000
2003	7276844000
2004	7818993000
2005	7751823000
2006	9219829000
2007	10747918000
2008	10609349000
2009	11853859000
2010	13498619000
2011	15097332000
2012	22101551000
2013	23957823000
2014	26265252000
2015	26657050000
2016	28030898000