I can't speak to quantities or rates, but I see a LOT of cigarette butts on the ground. This meme is right on target, in my experience.

My "favorite" was the time one threw their cigarette butt out the window of their car on a highway and it somehow ended up under the cowl of my windshield, so the smell was being sucked into my car by the ventilation system. And I couldn't easily get in there to remove it - I needed tools I didn't have on the road with me. At least it didn't start a fire.