According to Arstechnica, digital music sales made up only 2 percent of all music revenue in 2004; by 2008 sales jumped to 20 percent. Listeners can buy either individual MP3s or entire albums in MP3 format.
According to the Washington Post, CD sales fell 12.7 percent from 2009 to 2010. However, according to Breitbart, although CD sales have declined since 2005, they still account for 90 percent of the full albums purchased.
Although MP3s are somewhat of a new music medium, their sales are rising. Artstechnica estimates that the revenue generated by digital music sales will surpass CD sale revenue after 2010.