There's probably a way to grab that data from the developer API:
https://developer.riotgames.com/
But I don't know if any programmers have taken a shot at posting that SPECIFIC data on Lolking or elsewhere. I personally would like to know frequency of picks in OfA. I don't mean champs that win out, but all OTHER champs that were selected as well in champ select. Would help me get an idea of what queue times would look like for an OfA teambuilder queue. For example, if I knew that, say,
is selected 10 times every minute, that's a good sign it wouldn't be hard to get him in a teambuilder queue.