[dragonwriter]

> One source said there were 5.8 trillion cigarettes smoked globally in 2014. There's no way most of those get littered.... right?

Given my observation of people's smoking habits and the locations (or, mostly, not) of public facilities for the disposal of cigarettes, I'd say it's quite plausible that most got literates but only between 1/5 - 1/4 were smoked in a place where there was convenient access for disposal by someone who cared to use it.