I don't know about "active followers/day", but I've been looking at various random 10-in-series followers across my accounts and guestimating 3-4 legits per 10. The rest seem to be bots and IMers who are more interested in getting follow-backs. To further complicate things, "legits" could include good bot profiles and/or early-stage bots, but I don't have a quick way to tell.