I think the comparison goes somewhat like this: selling one CD puts X dollars in the creator's pocket. How many times need a track be played on Spotify to generate the same number of dollars? The answer is 471, I think.
Yeah, I was saying if you bought a CD you would pay $15 for 10 tracks, or $1.50 per track. You would have to listen to that CD 471 times for the cost per listen per track to reach what Spotify pays the artist per stream.