Year	2007 US$
1967	887500000
1968	397800000
1969	932900000
1970	1030000000
1971	2167000000
1972	2617000000
1973	2794000000
1974	5419000000
1975	3401000000
1976	2429000000
1977	4658000000
1978	3971000000
1979	4771000000
1980	6417000000
1981	5238000000
1982	6738000000
1983	6421000000
1984	6473000000
1985	7336000000
1986	4641000000
1987	7034000000
1988	9877000000
1989	5941000000
1990	8179000000
1991	9670000000
1992	8139000000
1993	9193000000
1994	9139000000
1995	10820000000
1996	11560000000
1997	11230000000
1998	9906000000
1999	8239000000
2000	8129000000
2001	7942000000
2002	7280000000
2003	6974000000
2004	7469000000
2005	8590000000
2006	7937000000
2007	8867000000