Americans conducted 14.8 billion core searches in April, a 3% improvement from March, as Google Inc.'s (GOOG) sites continued to dominate the search market, according to comScore Inc. (SCOR).

Some 64% of searches conducted in the month of April were on Google sites, with Yahoo Inc. (YHOO) and Microsoft Corp. (MSFT) having market share of 20.4% and 8.2%, respectively. IAC/Interactive Corp.'s (IACI) Ask network and Time Warner Inc.'s (TWX) AOL rounded out the top five, each with results under 5%.

Google accounted for 9.5 billion core searches in April, followed by Yahoo with 3 billion and Microsoft sites with 1.2 billion. Google's core search growth was 4%, with Yahoo up 2% and Microsoft up 1% from March's levels. Ask Network posted a 3% increase while AOL posted a 6% decline.

Meanwhile, in comScore's analysis of Web sites where search activity is observed, expanded searches posted a 5% gain to 22.1 billion from March. Google again lead with 13 billion searches, with Yahoo and Microsoft at 3.2 billion and 1.3 billion, respectively.

For friend networking sites, News Corp.'s (NWS) MySpace sites posted 15% growth to 658 million search queries and Facebook had a 28% drop to 176 million. MySpace, like Dow Jones & Co., publisher of this newswire, is owned by News Corp.

In e-commerce, Amazon.com Inc. (AMZN) sites down 2% to 188 million. EBay Inc. (EBAY) search queries grew 20%. Privately-held Craigslist Inc.'s search queries grew 4% to 583 million.

-By John Kell, Dow Jones Newswires; 201-938-5285; john.kell@dowjones.com