For the 1st half of this year, the sales of the digital music increase almost 50% to USD$ 417.3 million as compared to the same period of last year.
However, the sales of the pysical album has decreased 15%.
The shifting trend for digital music has been going on for the past few years in accordance to the individual preferences on selected music hits or singles instead of the music album as a whole. Besides, various e-tailers are providing online music sales like Amazon.com selling the DRM-free songs which may encourage users to go for digital music. The introduction of the new devices like iPod also contributed to this trend.
Source: TheNewYorkTimes Business - Digital Purchases Rise as Album Sales Fall