U.S. album sales continued to decline in 2006, down nearly 5 percent from the previous year, but total music sales were up thanks to a huge increase in digital downloads.

Year-end sales figures released Thursday by Nielsen SoundScan said 588.2 million albums were sold in 2006 — a 4.9 percent decline from 2005.

But digital track sales increased by 65 percent over the previous year, with 582 million tracks sold, and digital album sales more than doubled, with nearly 33 million sold last year.

The top-selling album of the year was a soundtrack inspired by the Disney Channel movie "High School Musical," which sold more than 3.7 million copies.

Another Disney-inspired soundtrack aimed at 'tweens — "Hannah Montana" — was the No. 8-selling album and sold nearly 2 million copies.

Albums by Rascal Flatts, Carrie Underwood, Nickelback and Justin Timberlake rounded out the top five.

For the first time ever, a digital song — "Bad Day" by Daniel Powter — sold more than 2 million copies in one year, thanks to the play it got as the send-off song on "American Idol."

Country group Rascal Flatts was the biggest selling artist in 2006, with nearly 5 million albums sold and nearly 4 million digital track sales.

Overall country album sales dipped by less than 1 percent.

Classical heartthrobs Andrea Bocelli and Il Divo helped give classical music the largest percentage sales boost of any genre — a 22.5 percent increase in 2006.