I would say that seems a little high. I would think more like a 18. I don't know, just thinking 20 seems pretty high.
I wont name names, but a guy from my high school had a UNL offer and it got yanked b/c he couldn't get a 20 on his ACT. He ended up at another D1 school.
I don't know what the base is first hand, but that is my experience with the issue.