Apple has revealed that iTunes Radio has reached 20 million users listening in to a billion songs since it launched in September.
Chief Executive Tim Cook made the update at an event in San Francisco on Tuesday.
After Apple said it had collectedin iTunes Radio's first five days of life, it took about 5 weeks to come within range of doubling the initial figure.
That indicates that many of those initial users were tire kickers, checking out Apple's long-awaited online radio service right after it launched with the rollout of iOS 7 and update to desktop iTunes software.
Pandora, by comparison, is the current leader in streaming radio with about 72.7 million active users as of last month, and it surpassed 200 million registered users earlier this year.
Streaming music -- a rare corner of growth for the otherwise beleaguered music industry -- is already a field crowded by the likes of Pandora, iHeartRadio, Spotify, Rdio, Google Music All Access, et al., but Apple's base of at leastiTunes customers worldwide and favorable relationship with labels gives it an advantage on those that came before.
Updated at 10:27 a.m. PT with further details and context.