Renay: Re the Nostalgia Machine, what years were you looking at? I grew up in Detroit, where Motown had a significant chunk of the pop-music pie, and yet when I looked at 1968 (the year I first started actively listening to pop radio), there was a lot less black music than I would have expected. So now I'm curious. Is this an artifact of where I was living, or of my own skewed perceptions, or what?