I have a list albeit a dated one I had compiled from SteemBotTracker for a previous project (calculating rep scores w/out bot votes) and I plan to get that rough figure. The last I heard it was somewhere around 30% of total voting power but that was a while ago.
I also agree that bid bots are detrimental to Steem in some ways with a few exceptions but I wouldn't put it so lightly personally. I tend to be against them for a number of reasons and think they are one of the biggest things that will hold Steem back personally.
I'll work on obtaining that figure and will let you know when I do. I may or may not opt to update my list but it was from a couple months ago so shouldn't have changed too much.
RE: Does anyone have any data on how much of the reward pool is currently controlled by bid bot use?