In website traffic.
"In a custom report created for ClickZ News, Hitwise measured traffic market share of the candidate sites.... RonPaul2008.com drew a 27 percent share of visitors to Republican candidate sites in May. MittRomney.com attracted almost 21 percent of visits last month, while John Mccain.com brought in almost 13 percent.
"Hitwise defines market share of visits within a site category as the percentage of traffic to a particular site based on its sample of 10 million U.S. Web users."
