Mobile search is still a small business, but Google is so far replicating the success it’s had on the computers. Of the 33 million U.S. mobile users who use a search engine on their phones, more than half say they use Google, according to comScore.

The next closest are Yahoo and the carrier's branded search portal, which about 20% of mobile searchers say they used. That can often be a carrier-branded Yahoo or Microsoft search tool, via deals like Verizon's with Microsoft.

These two sets of statistics are derived by different methodologies, which could lead to inconsistencies. For mobile search, comScore uses a survey methodology. This, plus the "carrier" option, could skew results in Google's favor -- and against Yahoo's and Microsoft's. For desktop search, comScore uses a behavioral methodology.