Year	Number of Incidents	Gallons Spilt
1973	11,054	15,289,188
1974	12,083	15,739,792
1975	10,998	21,528,444
1976	11,066	18,517,384
1977	10,979	8,188,398
1978	12,174	11,035,890
1979	11,556	10,051,271
1980	9,886	12,638,848
1981	9,589	8,919,789
1982	9,416	10,404,646
1983	10,530	8,378,719
1984	10,089	16,254,974
1985	7,746	18,675,137
1986	6,543	4,451,343
1987	6,182	4,331,612
1988	6,748	5,493,397

Source: U.S. Department of Commerce, Bureau of the Census, Statistical Abstract of the United State, 1990, Superintendent of Documents, Washington, D.C., p. 202.

The table above shows how many oil spills occurred in each year, and the total number of gallons that were spilt in all of the incidents combined in that year.

Towards the very end of the table, it seems that the number of accidents is now decreasing.  This can probably be partially attributed to new technology aimed at preventing oil spills.

From 1986-1988, the amount of oil spilt per oil spill also seemed to have decreased significantly from previous years.  Again, it seems that improved technology is working towards saving the environment.  Of course, some would argue that it is technology itself that requires the oil that it being spilt.