Year	US Dollars
1970	169292000
1971	204419000
1972	226991000
1973	256402000
1974	283127000
1975	343671000
1976	402643000
1977	500729000
1978	567286000
1979	740068000
1980	823664000
1981	1841817000
1982	3279544000
1983	3845184000
1984	4222439000
1985	5212470000
1986	6144435000
1987	7377390000
1988	7717005000
1989	7855590000
1990	8645221000
1991	9133604000
1992	9355556000
1993	9717487000
1994	10079644000
1995	10324069000
1996	10091746000
1997	10090611000
1998	10360525000
1999	5572315000
2000	5516257000
2001	5745842000
2002	6552441000
2003	7281810000
2004	6624003000
2005	6229313000
2006	2280741000
2007	2655245000
2008	2904266000
2009	5416187000
2010	7334516000
2011	8610052000
2012	10461905000
2013	12575129000
2014	16327986000
2015	20139846000
2016	23062955000