How Much Oil Has Leaked Into The Gulf?

What I don't understand is how does BP not know how much oil leaked into the Gulf of Mexico? According to this article, oil has reached the ocean floor on April 22nd. 5,000 barrels a day is estimated to be the amount of oil spilling into the gulf, which happens to be 210,000 gallons. It's said that the rate of the oil can go up. As of May 6th, there were 3,000,000 gallons of oil that have leaked into the Gulf. That's insane. Imagine all of the animals that have to suffer through this. I can't even begin to fathom why nothing is being done.