I think he is requesting info regarding an aggregate; i.e. if I have a sequence where a double street has repeated 4 times, and the two other double streets (in Low) have appeared only [1,2 or 3?] times, what are the chances that this double street will appear a 5th time before the other double streets hit 4 times. I would simply answer this question by creating this scenario in the random flow millions of times and counting how many times the 5th hit occurs versus the times it misses.
Ok, I think this has answered my question. He doesn't care how many times the other double streets have hit, he only cares that a double street in Low has repeated 4 times.
Ok I get it. This is easy to program and track.