New York—Radio revenue totaled $16.5 billion last year, up 1.0% over 2011, according to a report by the Radio Advertising Bureau.

In the fourth quarter, radio revenue hit $4.4 billion, up 4.0% over the year-earlier period. Political advertising helped fuel the gain.

Digital radio—while still representing only a small fraction of total radio revenue—grew 8.0% last year to $767 million.

The top advertising category in radio last year was automotive, which grew 29%. Advertising for TV, communications and restaurants grew 18% last year, and advertising by financial institutions rose 17%.

Data were provided by Miller Kaplan Arase and do not include network radio.