Year	US Dollars
1970	984933000
1971	1127927000
1972	1186061000
1973	1287838000
1974	1514188000
1975	2659520000
1976	3360847000
1977	5610349000
1978	6923296000
1979	8207899000
1980	9722124000
1981	10579565000
1982	12401137000
1983	13037496000
1984	13908395000
1985	16056154000
1986	17926463000
1987	21029567000
1988	21117135000
1989	22230853000
1990	25026513000
1991	22503088000
1992	22688198000
1993	22114998000
1994	22988002000
1995	23785010000
1996	24233323000
1997	23501648000
1998	23656719000
1999	23059606000
2000	20790302000
2001	18901345000
2002	18103550000
2003	18331891000
2004	17016928000
2005	16253549000
2006	17944740000
2007	20679213000
2008	20956808000
2009	24667544000
2010	27258909000
2011	29923639000
2012	33835732000
2013	39263300000
2014	42809481000
2015	42990393000
2016	46264659000