Digiton

The click-through rate for banner advertisements on major Web destinations such as Yahoo!, Microsoft and AOL declined from 0.75% to 0.27% during 2006, according to Eyeblaster, as cited in BusinessWeek. average click rate on standard banner ads across the whole Web was 0.2% in March 2007.

http://www.emarketer.com/Article.aspx?id=1005568