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	354767000
1993	387586000
1994	464446000
1995	530709000
1996	534110000
1997	606209000
1998	726729000
1999	981029000
2000	959974000
2001	946237000
2002	1102128000
2003	1544708000
2004	1593616000
2005	1396369000
2006	1494388000
2007	1741845000
2008	2183512000
2009	2985758000
2010	5927962000
2011	9626575000
2012	15384510000
2013	18892673000
2014	20826128000
2015	21542455000
2016	23912336000