Year	US Dollars
1970	162260000
1971	162114000
1972	159382000
1973	159152000
1974	161976000
1975	178683000
1976	208532000
1977	292111000
1978	443070000
1979	596484000
1980	685686000
1981	813445000
1982	902592000
1983	1006558000
1984	1080100000
1985	1250204000
1986	1549809000
1987	1847224000
1988	1817049000
1989	1877358000
1990	2062086000
1991	2187244000
1992	2176738000
1993	2237488000
1994	2367413000
1995	2489150000
1996	2423883000
1997	2406200000
1998	2561188000
1999	2588479000
2000	2836280000
2001	3035973000
2002	3293836000
2003	3632796000
2004	3862480000
2005	3950579000
2006	4191790000
2007	3777966000
2008	3160827000
2009	1850281000
2010	418852000
2011	448441000
2012	487153000
2013	530499000
2014	680542000
2015	836846000
2016	951620000