>>20403431>Did you just time travel from twenty years ago?Fuck, you found me out!
But seriously, though, wearing no bra is a more recent thing, so even if 90% of girls had pierced nipples, I wouldn't know most of the times, if they're hidden under a (padded) bra.
And while I don't have any numbers, I'd still guess that the majority of nipples by far is unpierced. The amateurs on the internet aren't a representative sample.