I usually follow every one of my followers back. If there is an imbalance its because of their inactivity....in which case I unfollow. Usual rule is cull people inactive for between 3-6 months. Someone really needs to invent a bot to alert us of unfollowers or inactive for specified periods. They have them for Twitter and Instagram...surely its capable here??
RE: I will unfollow all non-followers soon and thanks for over 275 Followers!