Year	US Dollars
1970	3406730000
1971	3795852000
1972	4072129000
1973	4566906000
1974	5121326000
1975	5752864000
1976	6802361000
1977	7564134000
1978	8329297000
1979	8918877000
1980	9931194000
1981	10580761000
1982	11703996000
1983	12026221000
1984	12227889000
1985	13464893000
1986	14954401000
1987	16797661000
1988	17065163000
1989	18348190000
1990	20663378000
1991	23363323000
1992	24917888000
1993	24546385000
1994	27382727000
1995	30228712000
1996	29834515000
1997	30078631000
1998	32283221000
1999	34142865000
2000	33021538000
2001	31914738000
2002	33806946000
2003	36464318000
2004	36331635000
2005	34017893000
2006	37174398000
2007	42006037000
2008	49523536000
2009	56339767000
2010	62801080000
2011	64468905000
2012	62066490000
2013	57881485000
2014	61146693000
2015	65757391000
2016	72697473000