Year	US Dollars
1970	3299810000
1971	3409739000
1972	3585308000
1973	4023443000
1974	5380537000
1975	6263822000
1976	7725085000
1977	9323180000
1978	9864919000
1979	9416573000
1980	9534079000
1981	8742796000
1982	10871147000
1983	11510205000
1984	12325640000
1985	13049985000
1986	15046005000
1987	17636120000
1988	18380471000
1989	18770834000
1990	20297682000
1991	20804190000
1992	20421071000
1993	23650217000
1994	26596517000
1995	30911666000
1996	29032994000
1997	29724009000
1998	30581704000
1999	29361511000
2000	28834465000
2001	27722609000
2002	28425471000
2003	30166301000
2004	31742551000
2005	29513669000
2006	29295980000
2007	32239017000
2008	34719590000
2009	37389856000
2010	42153894000
2011	45012108000
2012	54558515000
2013	56802792000
2014	61269605000
2015	65940554000
2016	69503047000