My own experience is the same. Our facebook page has over 2000 likes, our twitter feed has about 360 followers, but we only have 19 people following us on google+ (even though we've been on there for a year, post all the same things on google+ and promote our g+ page as much if not more than the others).

On a personal note none of my friends uses google+ (only my wife). They pretty much all use facebook.