NEW YORK (AP) — U.S. Internet advertising revenue grew 15 percent to a record $36.6 billion in 2012, with mobile ad revenue growing faster than other types, according to a new report Tuesday.

The report from the Interactive Advertising Bureau and PricewaterhouseCoopers said that mobile ad revenue more than doubled from the previous year to $3.4 billion. It accounted for 9 percent of total Internet ad revenue in 2012. In 2011, the $1.6 billion in mobile ad revenue made up 5 percent of the total. Mobile ads represent an area of growth for many companies, including Google Inc. and Facebook Inc. Facebook started showing mobile ads last year.