With the diversified revenue streams in the music industry, it becomes harder to accurately measure success.
When the industry was dominated by large, bureaucratic companies that all did business in basically the same way, it was straightforward to define and measure the industry as a whole—you just made a list of all the record labels and add up their revenues and profits. Today, a growing share of musical output is being produced by small firms or individuals with a much greater diversity in styles, quality, and business models. The lack of standardization makes it hard to summarize and measure how the industry as a whole is doing, which leads people to underestimate how much music is being produced and how much money is being earned.
What's actually happened is:
spending on entertainment grew from 4.9 percent of household spending in 2000 to 5.6 percent in 2008.