I have a question for you:
How many apps do you have?
What are your total number of downloads?
What are your total earnings?
This question being answered will help me and other developers receive insight on how much we should be making in admob considering we put well placed ads.
9 apps
2 apps more than 100,000 downloads, less than 1m
the others between 50,000 downloads
use admob
300-400 per day
hope this can answer your question.