Performers get zero payments for songs played on the radio (http://diymusician.cdbaby.com/2014/08/didnt-know-radio-royalties/). The authors of the songs (music and lyrics) do get paid. The payments to the rights holders (authors) of the music get paid from radio at a rate which is somewhere around $0.0003 per listener (give or take about 300% - source: http://davidtouve.com/2011/12/...).
In contrast, a permanent digital download and a CD (which can be played as many times as you like) have the same one time rate of $0.096 per track. This is set by law and is called a mechanical right.
So lets see what kind of relative value we have to a CD or PDD:
One radio listener, one listen = $0.0003, iow a permanent right "breaks even" at 320 listens
For Pandora and Spotify, they have to pay the entire chain - producers, artists, authors, promoters, etc.
If we scale the total fees using an album model, with a typical album costing $9.99 and having 12 tracks, of which 30% goes to the retailer, the value of a "track" is $0.583, or about 6x the amount paid for the author on that track. (you can argue the specifics, but if you're buying tens of millions of CDs worth of songs, you'd better get pricing that it *at least* this good)
So at that 58.3c/permanent track...
One pandora listener, one listen = $0.0014, break even is at 416 listens
One spotify listener, one listen = $0.007, break even us at 83 listens.
Radio has to play that track for 1920 listens to match the total compensation paid by the two streamers.
What does online streaming look like now? Pandora is slightly below Radio in their compensation per track to everyone they pay. You might contend that Pandora "finds" new artists better due to their model instead of radio playing whatever they're given to promote, and therefore provides slightly more value. Spotify, OTOH, lets you choose just what you want - you can play Brittney Spears all day, over and over - and therefore it's more like buying a track. And if you were to hit 83 plays on a track, you'd have been better off just buying the track. 83 plays seems like a lot, but that's over an entire lifetime - actually lifetime plus 70 years in copyright.