Year	US Dollars
1970	836678000
1971	960363000
1972	1081762000
1973	1778978000
1974	1880719000
1975	1687172000
1976	1337792000
1977	3146444000
1978	5091172000
1979	6244581000
1980	8938206000
1981	11445508000
1982	11992472000
1983	17576994000
1984	17783310000
1985	18655380000
1986	22215776000
1987	29024888000
1988	29624122000
1989	30121999000
1990	33458490000
1991	33526926000
1992	29018674000
1993	30699253000
1994	33092286000
1995	34094442000
1996	31414751000
1997	28467541000
1998	30313711000
1999	29095542000
2000	32374086000
2001	31418236000
2002	31780095000
2003	36711576000
2004	39898101000
2005	25754638000
2006	9617378000
2007	12144519000
2008	13128901000
2009	15942066000
2010	15484219000
2011	17663308000
2012	18127298000
2013	21143713000
2014	24755955000
2015	28942968000
2016	31151475000