Good question. I don't have a good ad stats program right now, and I charge a flat rate for banner ads on my site, so the honest answer is...I haven't checked!

Good question. I don't have a good ad stats program right now, and I charge a flat rate for banner ads on my site, so the honest answer is...I haven't checked! My ad service provider is going out of business on 12/31, so over the next few weeks I'll pick a different ad software program and/or ad service provider, and I'll then be able to track stats better.