It's 10% in the winter and 15% in the summer (at least that's the legal limit), although I think that's changing. So I guess they just said what the hell and put on both stickers?
Thomas midgley. He invented CFCs to replace the previously most commonly used refrigerants: Sulfur Dioxide and Ammonia which are both pretty nasty and should have been replaced... just not with CFCs. Leaded gasoline was invented to help prevent knocking and increase fuel efficiency. Today we use other additives and are better able to reform low octane hydrocarbons into higher octane ones with modern catalysts. Then as another commentater mentioned, he contracted Polio later in life and invented a sling and pulley system to help him out of bed.
And invented a bed with a bunch of wires and pullies for people who are crippled (after he got polio). Oh a good idea from the worst man ever you might think, NOPE this invention was also deadly and after a malfunction killed him.
So there's a shit load of caveats. One there's only a few places i know in the state that sell it. It's supposedly only for small engine purposes, and it's illegal to pump into a car. There's daily limits imposed by the gas station and weekly and yearly limits imposed by the state I think, but I never looked them up.