Why is it 9% or below and not 1%?
I can recall a couple of posters, psychic is one, who went in depth about changes to their FICO(s) when they let 1% report, 2%, 3%, and so on. At least one found their sweet spot at 5%. But it's certainly a YMMV thing. It might be 1% for one or 9% for another.
Guilty!!! Mine is at 4%. And I've tested it a few times.