Well, Mediaguide claims to monitor a range of US radio broadcasts, you can follow the link on the qliktech app to see what they do.
I played around with the genres, blues is predictable - Bad to the Bone and Pride & Joy come out top. Rock, well, is Nickleback really that popular in the US? I was assuming anything that surprised me was just the difference the ocean makes.
It gets weird on the When page. Supposed to segment by era, which is ok from the 1950s on, but they've got Pink and Kings of Leon in the 1920s.