The figure is the lowest since 1993, the first year SoundScan began compiling the numbers.
Individual song downloads grew only 1 percent, to 1.17 billion, after 7 years of double and even triple digit growth.
The top album for the year was Eminem's latest, "Recovery," which moved 3.4 million copies. That number is higher than any album has seen since 2007.
By comparison, Eminem's blockbuster 2002 CD "Eminem Show" sold 7.6 million copies.
As a collection, the 8 albums of the "Glee" series sold 3.6 million copies.
The top selling individual song was Katy Perry's "California Gurls," at 4.4 million copies.