Google said it was sharing the information "in the spirit of greater transparency."

"AdSense for content publishers, who make up the vast majority of our AdSense publishers, earn a 68 percent revenue share worldwide," Neal Mohan, vice president of product management at Google, wrote in a blog post."This means we pay 68 percent of the revenue that we collect from advertisers for AdSense for content ads that appear on your sites. The remaining portion that we keep reflects Google's costs for our continued investment in AdSense — including the development of new technologies, products and features that help maximize the earnings you generate from these ads."

On the search front, publishers keep 51 percent. "As with AdSense for content, the proportion of revenue that we keep reflects our costs, including the significant expense, research and development involved in building and enhancing our core search and AdWords technologies," Mohan wrote.

The content revenue shares have remain unchanged since its 2003 launch. Search policies have been in place since 2005, when Google increased it.

The news comes several days after the Federal Trade Commission closed its investigation of Google's purchase of online advertising network AdMob.

http://www.pcmag.com/article2/0,2817,2364161,00.asp