Get the latest news alerts: at Twitter.

AP, LTW

RESTON, Va. – Google Inc.’s sites continued to account for the vast majority of the U.S. search market in September, with rival Microsoft Corp.’s sites seeing a slight gain from August, according to

The Internet data analysis provider said Wednesday Google sites held 64.9 percent of the search market last month, up slightly from 64.6 percent in August. Yahoo Inc.’s sites lost half a percentage point, and held 18.8 percent of the U.S. search market. Microsoft’s market share, meanwhile, edged to 9.4 percent from 9.3 percent in August.

According to comScore, Americans made 13.8 billion searches in September, down 1 percent from August .

Of those searches, Google sites accounted for 9 billion followed by Yahoo! (2.6 billion), Microsoft sites (1.3 billion), Ask Network (541 million) and AOL (416 million).

for the full statistical breakdown.

Measuring search traffic is important because advertisers who place pitches alongside search results will pay more to reach a larger audience.

Google sites led the search market during the month, with 12.8 billion queries, followed by Yahoo sites with 2.7 billion queries and Microsoft sites with nearly 1.4 billion searches.

Microsoft’s Bing search engine, which launched in June in hopes of rivaling Google, did not see an increase in search queries from August to September.