Looking for numbers: app monetization through in-app advertising

Does anyone have experience with app monetization through in app ads? I am looking for numbers - and the homepages of the ad networks do not provide them :)

We have a small case here where we have about 3000 users, each of whom spends an average of 3 minutes per month in the app.Ii'm just wondering if there's anything worth to be earned with advertising or if it is way too small.

I am looking for concrete income together with a benchmark (MAU / etc. ) and the ad network used.