I would say the normal are between 1 to 9 followers a day, there are of course some exceptions and 13 for @ecency I would say it doesn't surprise me. I am not considering here the amount that unfollows - if that happens during the same day. On the other hand, the ones that are on top a rare. I haven't seen them during the past weeks but I have noticed that they have recently created the accounts and their first posts went "viral" over the past two days - which can explain the amount of followers. I am expecting @blockheadgames to be getting approx 30 or above for today's stats (12th of Nov.) and there will be a gap between that account and the rest. Let's see.