I hope you will excuse my facetious reply from yesterday. I like statistics and number crunching, but is this all a bit pie in the sky, I mean, how many people have their windows cleaned, and by how many window cleaners? It's as long as a peice of string really isn't it? I can't see you getting the info you are after. I bet there are far more window cleaners not in yellow pages than are, and how many are not even legit. I would be interested in what figures you come up with.