I think “normal” depends on your industry! Sprout has a report about industry standards, but I’m not sure if it includes follower growth rate.

Our LinkedIn Company page is B2B and B2C, and over the past year we’ve averaged about 450 new followers per month. LinkedIn is definitely our fastest growing network! 

Agreed - it depends on the industry, exposure (tradeshows, advertising, etc), hiring, and probably much more. We average about 132 followers per month, but seeing more right now with more exposure in various places. Hope this helps!