Google announced yesterday they have added impression charts to the ad review center in Google AdSense. This is to show publishers how many impressions those ads are getting before they decide to block the ads from showing on their web site.
Google wrote:
Based on feedback from our publishers, we’ve replaced the previous interface with an impression chart that shows the absolute number of impressions and its distribution over time. When you’re considering blocking an ad, the impression chart can help you make a more informed decision by highlighting the potential revenue impact it may have.
Here is a sample:
Forum discussion at Google+.