Year	constant 2015 US$
1960	223480000
1961	169060000
1962	120940000
1963	92610000
1964	38800000
1965	50530000
1966	11820000
1967	9340000
1968	5590000
1969	22330000
1970	37010000
1971	32630000
1972	37280000
1973	35380000
1974	87110000
1975	109330000
1976	191250000
1977	296160000
1978	133390000
1979	74070000
1980	119080000
1981	105990000
1982	72250000
1983	43650000
1984	40480000
1985	81170000
1986	67760000
1987	72680000
1988	72370000
1989	67160000
1990	58060000
1991	58510000
1992	36520000
1993	48150000
1994	60790000
1995	26790000
1996	29100000
1997	55070000
1998	46710000
1999	73840000
2000	83570000
2001	74240000
2002	50940000
2003	17680000
2004	67710000