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	79649873000
1993	112440384000
1994	122341256000
1995	122049340000
1996	126999354000
1997	128143834000
1998	175719273000
1999	180043059000
2000	146665111000
2001	141151650000
2002	138446861000
2003	185905049000
2004	214206936000
2005	249832035000
2006	311265307000
2007	416308043000
2008	419280877000
2009	406431158000
2010	417841892000
2011	544308023000
2012	591785651000
2013	668458628000
2014	549592362000
2015	467688298000
2016	524685938000