These Web traffic stats follow market share reports from the likes of IDC and Gartner showing Windows Phone shooting past BlackBerry to achieve third place in the global smartphone arena. iOS is still the top dog, according to Chitika, with 53.1 percent of North American Web traffic. Second-placed Android isn't too far behind with 44.5 percent.

To derive its data, Chitika looked at hundreds of millions of ad impressions among smartphone owners in the US and Canada from February through April.