Internet ad revenue in US at all-time high

(CBS/AP) NEW YORK — A new report says revenue from Internet advertising in the U.S. hit a record $31 billion last year.

That's up 22 percent from $26 billion in 2010, the previous record.

The report was released Wednesday by the Interactive Advertising Bureau, an industry group. The study was conducted with PricewaterhouseCoopers.

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About half of the ad revenue, $14.8 billion, came from the search category. Those are the text-based ads sold by Google (GOOG) and others, which are targeted to search terms and other keywords.

The fastest-growing category was mobile, with revenue of $1.6 billion in 2011, more than double the $600 million a year earlier. It's still a small part of overall Internet advertising, however.