Year	US Dollars
1970	158332000
1971	195526000
1972	221180000
1973	256096000
1974	351485000
1975	451043000
1976	442651000
1977	837190000
1978	1024363000
1979	1278415000
1980	1572743000
1981	1806703000
1982	1948504000
1983	2237518000
1984	2407553000
1985	2856022000
1986	3098894000
1987	3419826000
1988	3426285000
1989	3492340000
1990	3816726000
1991	3483449000
1992	3970305000
1993	4432303000
1994	4792475000
1995	4910017000
1996	4806148000
1997	4942994000
1998	5099265000
1999	5582559000
2000	5614351000
2001	5158149000
2002	5491476000
2003	5656933000
2004	6205543000
2005	5170225000
2006	3987696000
2007	2999794000
2008	3489096000
2009	3805641000
2010	3976633000
2011	4387607000
2012	5054988000
2013	6830943000
2014	7328842000
2015	7585208000
2016	7579336000