The number of online advertisers and search engine marketing firms saying click fraud was a serious issue increased threefold in 2005 from the previous year, according to the December 2005 "State of Search Engine Marketing" report by the Search Engine Marketing Professionals Organization (SEMPO), writes ClickZ. "It's not so much that it's getting worse, but there is a heightened awareness about it," Kevin Lee, chairman of SEMPO and cochairman of its research committee, is quoted as saying.

Some 16 percent of advertisers and SEMs say they track click fraud and agree that it's a significant problem - up from 6 percent in 2004 - and 23 percent of advertisers and 33 percent of SEMs say they track click fraud and it is a moderate problem; a third say they are not tracking click fraud but are concerned. Only a quarter of advertisers and 18 percent of agencies say it is not a significant concern.

Among those who had experienced click fraud, 78 percent of advertisers and 59 percent of agencies say blamed publishers, networks or affiliates attempting to increase revenue; slightly more than half of advertisers and 41 percent of SEMs blame "competitive click fraud," (that is, competitors' clicking on an advertiser's ads).