I'd like to add something else to this suggestion (apologies for the necro). Beyond just statistics, it might be useful to see how many reports a specific moderator may have resolved/rejected in a given time period. I searched for an addon to do this, but as far as I've seen, nothing has surfaced.
I currently pay my moderators on a per-report basis. Unfortunately, at this time, I have to hand count how many reports were resolved and tally them up manually. An automated system would really improve productivity.
Apologies if a system like this already exists, I haven't been informed as such.