Sure, agree completely, although I wonder why you believe I may not know that? Yet lots of houses bought pre-punched paper, or just didn't use ring binders.
The 18% is just a throw out number, and the concept is a joke, yet... I'm sure there was some increase in hole punch purchases.
Because...
I bought one as a kid, after getting tired of cutting a ragged hole with scissors.
The only pre-punched paper we had when I was a kid was the notebook paper that was a required purchase on the school supply list. I remember using that as a template for punching holes in paper with a hole punch (since the fancy three-hole punch was something that only existed in the admin wing of our high school).