I'm not totally familiar with the data set, but it would be nice to plot more things from it. For instance, what were the chords that were popular during certai

I'm not totally familiar with the data set, but it would be nice to plot more things from it. For instance, what were the chords that were popular during certain years? You mention that the chords have changed, what does that graph look like? Is there any correlation between, I dunno, the DJIA's derivative and the 'sounds' of popular music. Great work though! I really like the clear and informative data displays.