Year	US Dollars
1970	501773000
1971	701049000
1972	939925000
1973	1019657000
1974	1278107000
1975	2104263000
1976	2712756000
1977	3425066000
1978	4166917000
1979	4955504000
1980	6610722000
1981	9179631000
1982	13353768000
1983	17553908000
1984	18737476000
1985	20273081000
1986	21882901000
1987	22841643000
1988	18569336000
1989	16279833000
1990	15329832000
1991	17080598000
1992	20018184000
1993	26148472000
1994	30335877000
1995	34342562000
1996	39673262000
1997	47228241000
1998	42409220000
1999	41976337000
2000	41946128000
2001	45157951000
2002	48343648000
2003	50773204000
2004	60510496000
2005	64911362000
2006	70050746000
2007	84215420000
2008	106896007000
2009	119611354000
2010	133799555000
2011	144898454000
2012	193879982000
2013	188794797000
2014	196587380000
2015	190951399000
2016	200364305000