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	34979000
1993	1727752000
1994	2789564000
1995	3750246000
1996	2922217000
1997	4077950000
1998	6074809000
1999	6600353000
2000	12890153000
2001	15339983000
2002	18437238000
2003	23226794000
2004	33233116000
2005	43857020000
2006	74429318000
2007	96232044000
2008	106730797000
2009	109734323000
2010	119144529000
2011	124324804000
2012	135526528000
2013	149703945000
2014	157694989000
2015	153381212000
2016	163757713000