There are various Web sites and posts to wit that the Exxon Valdez is the 35th worst oil spill. The worst was during Gulf War I when Saddam Hussein dumped 500 million gallons. There was a 140 million gallon oil spill in 1979, in the Gulf of Mexico, the IXTOC I that spewed for nine or ten months. The Exxon Valdez was about ten million gallons. On an average year, there are about 250 million gallons spilled from various factors. No estimate of natural seeps, which are substantial. Drilling reduced the pressure which reduces the volume of natural seeps. Very complicated and emotional subject. There have also been major leaks from pipelines that went undetected for years. For some of them there are no estimates of any reliability.