Year	US Dollars
1970	1801616000
1971	2049120000
1972	1952426000
1973	1991612000
1974	2209482000
1975	4835412000
1976	6357335000
1977	11733543000
1978	12857845000
1979	14905846000
1980	19130728000
1981	22077856000
1982	27323625000
1983	30213009000
1984	32187452000
1985	36124648000
1986	39891261000
1987	44151537000
1988	46148552000
1989	45676108000
1990	33015763000
1991	32604278000
1992	31168992000
1993	30651246000
1994	32499135000
1995	33475211000
1996	31512675000
1997	29952923000
1998	32297027000
1999	31079798000
2000	29195236000
2001	28297377000
2002	29632235000
2003	30421582000
2004	31358191000
2005	30538145000
2006	30984860000
2007	34551447000
2008	33892718000
2009	35415768000
2010	36833666000
2011	35236442000
2012	40089690000
2013	46562030000
2014	41826538000
2015	48459014000
2016	67214081000