Transportation fuel use is about 6 billion barrels per year or about 240 billion gallons per year. Check my math but that means about 10 thousands square miles of sewage filled plastic bags floating along our coasts.
I show 240 billion/2.5 million = 96,000.
192,000 square miles.
That's an unfortunate figure. That would be one third of the surface of the Gulf of Mexico. I think the cost of the environmental impact study for that alone would buy a year's worth of petroleum.
Using your numbers that works out to 0.138% of Earth’s ocean surface.
Thanks, I should have pulled out the abacus.