The overall click fraud rate was 15.8% for Q2 2007, up from 14.1% in Q2 2006 and 14.8% from Q1 2007, Click Forensics said. The rate for pay-per-click ads appearing on search engine content networks, such as Google AdSense and the Yahoo Publisher Network, was 25.6%, up from 21.9% in Q1 2007.