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	0
1993	968283000
1994	1296123000
1995	1693748000
1996	1958927000
1997	2082344000
1998	2386479000
1999	2703258000
2000	2620197000
2001	2798732000
2002	3399006000
2003	3779551000
2004	4601439000
2005	5300177000
2006	6562104000
2007	12526108000
2008	15152844000
2009	22078687000
2010	28412148000
2011	33932546000
2012	33755736000
2013	39573469000
2014	40013831000
2015	37934720000
2016	37515486000