Very scary. I heard this number before, yet I hope it is just an exaggeration.
It's not even the specific number that's scary. It's the fact that there is any number/group of people who find it 'acceptable' to do this on shabbos.
And it's scary because a lot of these kids would never drive on shabbos or eat not kosher in a million years. It's kind of just this one thing.
It's also because it's so easy to do in private.
And I can't imagine it's easy to stop once you start.