comScore, May 2011 qSearch analysis of the U.S. search marketplace data reports that Google Sites led the explicit core search market with 65.5% (up 0.1 percentage), followed by Yahoo! Sites with 15.9%, Microsoft 4.1%.
Over 17.0 billion explicit core searches were conducted in May (up 5% vs. April). Google ranked first with 11.2 billion searches (up 5%), followed by Yahoo! 2.7 billion (up 5%), Microsoft 2.4 billion (up 4%).
Google accounted 63.3% of total core search queries conducted, followed by Yahoo! 19.6% (up 1.7 percentage) and Microsoft 13.1%.
Also, note that Americans conducted nearly 19.3 billion total core search queries in May (up 7%). Google ranked first with 12.2 billion searches (up 5%), followed by Yahoo! 3.8 billion (up 17%) and Microsoft with 2.5 billion (up 1%).