Obviously I don't have statistics, but I've certainly covered up more than I've given. It's the single biggest reason people want cover-ups.
Point is - at a young age we're invincible and full of certainty that this is who we are and what's true for us now, will remain so for the rest of our lives - much less so when we've lived and matured a little. And it'd suck hard to carry something around in your skin that makes you feel like a fool for either having been silly, young and idealistic, or worse; having had your trust broken or your tribute ignored. While I'm all for expression in tattoos, there are certain things that are more lasting than a teenager's feelings.