With Adele's album "25" breaking sales records, one of the keys to the British singer's success is an unusual pop music demographic -- older adults.

The buyers of "25" come from "a demographic not normally closely examined in the millennial-fixated entertainment industry," sales tracking service Nielsen Music said in a study.

US consumers who bought the CD of "25" in its first week were 36 percent more likely than the average American to be between ages 55 and 64, Nielsen Music said.

They also skewed wealthier, with buyers of "25" two thirds more likely to have a household income above $100,000 a year.

However, the study did not look at who bought "25" on iTunes, and could presumably be younger.

Nielsen Music released the data late Thursday as it announced that "25" had sold more than five million copies since its release on November 20.

The album becomes the first to sell five million within a calendar year since "21," the previous album by Adele, in 2011.

Adele, best known for her ballads of heartache, is often said to enjoy such phenomenal success by her ability to appeal across ages and backgrounds.

By contrast, many other leading pop stars including Taylor Swift -- the best-selling artist in the United States in 2014 -- market themselves largely to a young, including pre-adult, audience.

Sharp-tongued British rocker Noel Gallagher of Oasis fame recently cited Adele's appeal to an older demographic as he denounced her work.

"I just don't see what all the fuss is about. I don't like her music. I think it's music for fucking grannies," Gallagher told Australia's Music Feeds site.

In the artists' native Britain, "25" broke the single-week sales record set by Oasis for the 1997 album "Be Here Now."

With "25" hugely anticipated, Adele's label made the unusual decision not to make the album available on online streaming sites, obliging fans to buy it.