Stern is still on the radio?
I thought he went satellite..
I would guess even satellite radio gets ratings. Also there may be a terrestrial radio rebroadcast.
Not all 5000 AM stations are news and talk. So 15,000 hosts may be an overestimate. On the other hand, some FM stations are news/talk - I would guess satellite too but there aren’t that many of them.
News/talk does attract conservative listeners so it should not be regarded as a cross-section of the voters.