The music industry can boast sales of more than 1 billion units in 2005, but only digital sales were a bright spot in an otherwise down year, according to year-end figures released Wednesday by Nielsen SoundScan.

Continuing the trend away from retail stores and toward iPods and mp3 players, 620 million albums were sold last year, down 7.2 percent from 2004.

"It was a year where you had to deal with the problems of piracy and the fact that there weren't that many big stars releasing records," said Doug Morris, chairman of Universal Music Group.

A record 352.7 million digital tracks, however, helped boost otherwise sagging results. It was a 150 percent jump from last year. Similarly, digital album sales leapt 194 percent from 2004, with 16 million-plus sold.

"It's going to explode the business, and it takes a while to do that," Morris said of the digital technology. "It's a great time for the business. It's incredibly interesting to be a part of this revolutionary change."

Geoff Mayfield, director of charts at the music trade magazine Billboard, said 2005's downloading sales were still secondary to album sales.

"Digital distribution represents the future and it represents optimism. At the same time, the album — the physical album — carries the mail," Mayfield said. "While downloads are sexy and they certainly had a robust year of growth ... physical albums are still the moneymaker."

In total — counting albums, singles, videos and digital tracks — the music industry racked up more than 1 billion sales for the first time ever. Still, most of that increase was due to the high number of digital tracks sold.

Of those albums physically bought, 24.7 million were purchased over the Internet, an 11.3 percent increase over last year.

Mariah Carey ended the year with the top-selling album — 4.9 million copies of "The Emancipation of Mimi." Buoyed by eight Grammy nominations, a rush of sales late in the year catapulted her past 50 Cent's "Massacre," which sold 4.8 million.

The most popular digital track was Weezer's "Beverly Hills," while Green Day was the top-selling digital act overall. The punk band sold nearly 3.5 million downloaded songs.

Virtually all individual music genres decreased in sales. The only genre to improve over its 2004 numbers was Latin music, which increased by 12.6 percent. The most precipitous drop-offs were in soundtracks, classical and metal.