Year	US Dollars
1970	0
1971	0
1972	0
1973	0
1974	0
1975	0
1976	0
1977	0
1978	0
1979	0
1980	0
1981	0
1982	0
1983	0
1984	0
1985	0
1986	0
1987	0
1988	0
1989	0
1990	0
1991	0
1992	550692000
1993	3855491000
1994	5636654000
1995	8429952000
1996	9538675000
1997	11133854000
1998	13068986000
1999	15747796000
2000	13909675000
2001	22203221000
2002	23480138000
2003	25860632000
2004	32104403000
2005	35095346000
2006	54264718000
2007	80748370000
2008	99354541000
2009	105064101000
2010	124297079000
2011	136907923000
2012	133514087000
2013	149104046000
2014	129020923000
2015	121332110000
2016	117983248000