Max Administrators?

Is there a maximum number of administrators, and how do you get around it in larger maps?

I got to a point where I couldn't create any more due to too many being idle, and couldn't seem to do anything about it.

Gotta say, at this point, the administrator thing is my least favorite change, because if you play on big maps, you're going to pretty much be limited to only making administrators for a long, long time, and it kind of makes the whole citizen thing useless.  This mechanic doesn't seem to scale based on map and/or other factors (I'd hate to bump up abundancy, for ex).