My point is that for internal competition, using a comparison to other members as a target is never going to end well. In the end, the 'average' figure is a pretty meaningless value.
Instead, I think it's more important to target a standard. E.g. a minimum level of literacy/numeracy. "50% of our children can't spell" is a much more meaningful statement. Now as for how you measure that... that's a whole other problem.