You could also check out the Unofficial Dynamic Range Database
http://www.dr.loudness-war.info/
And two interesting articles on the matter, which seem to have contra-intuitive results regarding the "loudness wars"
Dynamics: evolution over the years, distributions
Dynamic Range & The Loudness War
We all know music is getting louder. But is it less dynamic? Our ground-breaking research proves beyond any doubt that the answer is no — and that popular beliefs about the ‘loudness war’ need a radical rethink.