Autonumber Until Certain Value then Restart

I hope I can articulate clearly what I'm trying to do.

So I have a list of data that I do not know the length of in advance. I need to automatically number each entry (the entries themselves make no difference) to a certain number and then start back at one. So say I have a list of 9 entries and I want them to label 1, 2, 3, 4 and then on the 5th entry is starts back at one, then at the 9th entry it's 1 again and so on for longer lists. My mind just isn't wrapping around the code for this. I've attached a sample workbook with what I've thought of so far but I just don't even know where to begin to get it to start over. I've tried nested for-loops but I get errors....