I don't think I've ever seen a PSA on my site, so 20% PSAs wouldn't be normal for me. Whether it's normal overall is hard to say; in any case, averages are meaningless since different topics and subtopics will perform differently.
Is your site new? If so, you may see better targeting after it's been around a while.
Msg#: 1050 posted 10:36 pm on Nov 12, 2003 (gmt 0)
I have about 8% of PSA accoring to the stats of alternate ads. I am using CJ.com for alternate. Many of the pages w/ PSA, I think, were not visited for a long time and haven't been visited by Media bots. I think the visits by users trigger the mediabots' visits.