Year	constant 2015 US$
1966	89180000
1967	97640000
1968	113220000
1969	112830000
1970	121240000
1971	113440000
1972	136000000
1973	204200000
1974	148030000
1975	220110000
1976	239800000
1977	242510000
1978	221820000
1979	300930000
1980	296530000
1981	314310000
1982	400250000
1983	434590000
1984	450380000
1985	439250000
1986	463480000
1987	466720000
1988	504830000
1989	455770000
1990	340850000
1991	412760000
1992	398330000
1993	427660000
1994	458650000
1995	500040000
1996	452860000
1997	465640000
1998	469950000
1999	464260000