There was no sophomore slump for the Backstreet Boys [ tickets ] in 1999, according to album sales-tracker SoundScan: "Millennium," the polished boy-group's follow-up to its self-titled 1997 debut, sold better than 9.4 million copies, earning honors as the top-selling album of the year.

Second place on the 1999 SoundScan chart, which covers point-of-purchase album sales between Jan. 4, 1999 and Jan 2, 2000, belongs to ''...Baby One More Time,'' the first release by Britney Spears [ tickets ]. With more than 8.35 million copies sold, the album is the best-selling ever by a teenage act, according to the Recording Industry Association of America.

Ricky Martin [ tickets ] easily made the crossover from Spanish-language success to stardom among English-speaking fans, his self-titled album selling 5.9 million copies. Again crossing over from the country music charts was Shania Twain [ tickets ], whose two-year-old album ''Come On Over'' sold 5.6 million in 1999, according to SoundScan. ''Come On Over'' is the second-best selling album of the SoundScan era--which dates from 1991--trailing only Alanis Morissette [ tickets ]'s 1995 release, ''Jagged Little Pill.''

Alternative rock's best-selling album of 1999 was Limp Bizkit's ''Significant Other,'' which sold 4.95 million copies, according to SoundScan. Santana's ''Supernatural,'' which is nominated for 10 Grammy awards, sold 4.7 million copies in 1999 thanks to the break-out single ''Smooth.''

Rounding out the year's top 10 albums were ''Devil Without A Cause'' by Kid Rock, TLC's ''Fanmail,'' Christina Aguilera's self-titled debut and ''Wide Open Spaces'' by Dixie Chicks.

According to SoundScan, 754.8 million albums were sold in 1999, up from 711.0 million in 1998 (top sales categories are listed below).

Just five record label distribution groups accounted for nearly 84% of the albums sold in the U.S. in 1999. The Universal Music Group, including Interscope, Geffen, MCA and Island Def Jam, retained its position as the top album distributor with a 26.4% according to SoundScan.

In second place was Sony's distribution arm, despite a slight drop in market share to 16.2%. The Bertelsmann Music Group jumped from a 12.2% market share to a 16% share, thanks to the success of teen favorites the Backstreet Boys and Britney Spears. BMG was 1999's No. 3 distributor, up from No. 5 the prior year.

The Warner distribution group, which didn't have new releases from many of its top artists, fell from an 18.2% market share in 1998 to a 15.7% share in 1999. EMI Music Distribution, which distributes the struggling Capitol labels among others, fell from a 13% share in 1998 to a 9.5 share in 1999.