"She really crossed over from pop to Latin to adult contemporary to dance," he added. "Young and old consumers bought it, and because of its mixture of fans, she was able to sell it as well as she did."

Adele's success came despite the drop in 2012 US album sales.

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"Last year (2011) was a fluke," Caulfield said. "A year gain in album sales is a mega achievement. ... It's the way the market works now, people buy songs and not albums."

Indeed, digital song sales rose 5 percent in 2012 to a record high 1.336 billion downloads.

The year's best-selling albums in the United States had a particularly British flavor as Swift was the lone American in the top five. Swift records for the independently owned Nashville-based Big Machine, distributed by Universal Music Group.

British boy band One Direction's "Up All Night," released in 2011 on Sony Music Entertainment's SYCO/Columbia label, placed third with 1.62 million units sold, while their 2012 follow-up, "Take Me Home," took the fifth spot with 1.34 million units sold.

Britain's folk revivalists Mumford & Sons, on indie record label Glassnote, placed fourth with their album "Babel" selling 1.46 million units.