"the number of people who click on display ads in a month has fallen from 32 percent of Internet users in July 2007 to only 16 percent in March 2009, with an even smaller core of people (representing 8 percent of the Internet user base) accounting for the vast majority (85 percent) of all clicks."

“Only 8% of internet users now account for 85% of all clicks on display ads,” comScore and Starcom USA study