I want to know the answer to the following question:
What has caused a decrease in CD sales?
All the background I'm provided with is that "For example, between 2000 - 2008, despite overall growth in music sales and one anomalous year of increase, major-label CD sales declined overall by 20%, although independent and DIY music sales may be tracking better according to figures released 30 March 2009, and CDs still continue to sell greatly.". Is that enough to answer the question?