The Visualist Capitalist website has posted a great graph showing music industry sales in the USA in $ (adjusted for inflation) over the past 40 years. It shows that music sales revenue peaked in the late 90’s, with CDs making up over 95% of the market in 2002, before MP3s and streaming services came online in a big way. Music revenue has started to increase again after years of decline, and physical media sales make up less than 20% of sales now.
Check out the graph and article at: