Year	US Dollars
1970	0
1971	48816000
1972	99160000
1973	258063000
1974	375393000
1975	440332000
1976	535433000
1977	723294000
1978	926936000
1979	1175002000
1980	1685753000
1981	2041164000
1982	2404746000
1983	2797978000
1984	3003217000
1985	3340617000
1986	3883335000
1987	4587003000
1988	5247813000
1989	5594815000
1990	6354024000
1991	6475142000
1992	6573076000
1993	5944864000
1994	6153590000
1995	6250656000
1996	6399961000
1997	3917094000
1998	5778378000
1999	5132267000
2000	5152421000
2001	5187678000
2002	5323448000
2003	5480632000
2004	5603366000
2005	5477561000
2006	5713773000
2007	6155424000
2008	6228634000
2009	6799205000
2010	6492701000
2011	6417662000
2012	7718089000
2013	7569770000
2014	7818019000
2015	7287189000
2016	7065832000