Looking further, it looks like people are being extremely picky when approving or rejecting changes, which is great. That's exactly what we want, because it means we can achieve extremely high quality with the data. We won't have the problem of items sitting in the queue for too long once we add a lot more moderators, as changes won't take near as long to get approved or rejected.
Going forward we're going to add an automated system where you gain moderator status automatically after a certain number of approved changes. This way you to have to prove that you are capable of making quality contributions, while also allowing us to grow the moderator base so that everything is truly community-moderated.