Year	2007 US$
1967	7301000000
1968	5497000000
1969	939300000
1970	1319000000
1971	4082000000
1972	3686000000
1973	3698000000
1975	3862000000
1976	3522000000
1978	5010000000
1979	5531000000
1980	6147000000
1981	5392000000
1982	5469000000
1983	6581000000
1984	8941000000
1985	5629000000
1986	5190000000
1987	5026000000
1988	5049000000
1989	5068000000
1990	5897000000
1991	5712000000
1992	5316000000
1993	4889000000
1994	6181000000
1995	5655000000
1996	4290000000
1997	4524000000
1998	4884000000
1999	7010000000
2000	8175000000
2001	6664000000
2002	8816000000
2003	13360000000
2004	19850000000
2005	17910000000
2006	17320000000
2007	18620000000