I can't tell you how many or which in the global market, because I have no idea and would only speculate. I only have an idea on the numbers in the country I l

I can't tell you how many or which in the global market, because I have no idea and would only speculate. I only have an idea on the numbers in the country I live where I work for an online only news website that makes all the revenue with only advertisement. I think I'm safe to say that we are talking about websites that are big enough to have a small team with at least one "Ad Sales Rep". The Sale representitive will go directly to companies and sell ads either by impression (CPM) or a flat rate for a fixed period of time. Since the amount you can sell a flat rate for a week/day/month is based on your number of impressions/users is basically another kind of CPM sale.