Year	US Dollars
1970	7097272000
1971	7627450000
1972	8351504000
1973	10667131000
1974	14080544000
1975	18381409000
1976	24139106000
1977	31382400000
1978	35905340000
1979	42974451000
1980	57574362000
1981	78412643000
1982	86274651000
1983	93158281000
1984	95016519000
1985	97063213000
1986	101083076000
1987	109652607000
1988	99399527000
1989	94016246000
1990	104604453000
1991	114219788000
1992	112454853000
1993	131852495000
1994	139914918000
1995	166734031000
1996	157582823000
1997	148844862000
1998	160179815000
1999	167974626000
2000	152557989000
2001	166064502000
2002	157273701000
2003	158672304000
2004	165905777000
2005	170823244000
2006	170608370000
2007	196080703000
2008	197671890000
2009	193342946000
2010	245906481000
2011	291784444000
2012	349269385000
2013	406420410000
2014	442271727000
2015	426434950000
2016	422656826000