Here are some links to articles summarizing academic research on how the cultural sector, including the music business, has fared in the file sharing era.

First, three studies on the music business in various member states:

• Sweden 2000 – 2008: More Charts The Record Labels Don’t Want You To See: Swedish Musicians Making More Money
• Norway 1999 – 2009: Artists Make More Money in File-Sharing Age Than Before It
• UK 2004 – 2008: Record companies lose, artists gain from file sharing

The three studies all paint the same picture: The revenues for the record companies have dropped by about half in the last decade, but at the same time, revenues for artists have gone up. The links above are to short articles summarizing the studies. In each case, the article contains further links to references.