Via Digital Music News 30 Years Of Music Industry Change, In 30 Seconds Or Less… Each pie chart shows 1 year, from 1980-2010, based on RIAA revenue figures for the revenue contribution from various formats.
US-based data of total recording revenue. And, here are the individual year source images, starting with 1980 on the top left and 2010 on the bottom right. Just pick a year and go, and download whatever you need.
Hat tip Josh