The just-released
Edison Report indicates that

72 percent of all Americans over the age of 13 are reached by Broadcast radio (AM/FM) each day.
90 percent of all Americans over the age of 13 are reached by Broadcast radio (AM/FM) each week.

Among listeners 18-24, Internet radio accounts for 29% of listening. Broadcast radio (AM/FM) accounts for 71%.

Among listeners 25-54, Internet radio accounts for 18% of listening while Broadcast radio retains 82%.

A snapshot of all listening indicates that – at any given moment – 85 percent of the total, combined audience will be listening to a Broadcast radio station and 15 percent will be listening to one of several Internet radio outlets, with Pandora being the 900-pound gorilla, accounting for about two-thirds of all Internet listening.

(This means Pandora currently accounts for about one-tenth of all radio listening.)