That may be a case of those who answered with the phrase “Jazz” versus a specific artist. IE, dumb people who wanted to appear smart and sophisticated so they answered jazz.
Also, for vertical placement, I understand that they can't pile up all the "middle answers" on top of one another, but someone decided that Greenday was going to be in the lowest row, and Coldplay was going to be in the highest row. They ought to have some criteria for that decision process. This looks like something an eighth grader put together.
Or they were Kenny Gorelick fans that he is a jazz artist and are afraid to admit they like him. So they just say they liked jazz....