This is by no means a quantitative study, but I live in the U.S. (in a fly-over state, none the less), have very little connection to the arts and every friend I can think of, off the top of my head, knows who banksy is.
It's obviously a pretty self-selected population, and I mean, I haven't formally surveyed all of my friends, but there you have it, for what it's worth.
I like Banksy, but there's no way my mom knows who he is, which is the important thing. There are more "my moms" in the U.S. than there are "your friends", in other words.
That's true, and like I said, none of this is a quantitative assessment.
I think phrasing is that way is misleading, though, there are more "my friends" than "my mom" even though they each have a "my mom."
I would wager that the sum total of all twenty and thirty somethings that know of banksy is pretty substantial. That said, it's definitely not a household name. I'm just wondering if 98% is a great guestimate.
It's all wild speculation, though and kind of immaterial
It's obviously a pretty self-selected population, and I mean, I haven't formally surveyed all of my friends, but there you have it, for what it's worth.