Pop rules best-selling iTunes songs of all time: Lady GaGa, Black Eyed Peas

Lady GaGa's "The Fame"

As iTunes nears it's 10 billionth download sale, the Apple-owned company is celebrating by pulling back the curtain on its best-selling songs of all time.

And, yes, you read that right: 10 BILLIONTH.

Unsurprisingly, it's mainstream pop titles that rule the school, like Black Eyed Peas smash singles "I Gotta Feeling" and "Boom Boom Pow."

"I Gotta Feeling," Black Eyed Peas
"Poker Face" Lady Gaga
"Boom Boom Pow" Black Eyed Peas
"I'm Yours" Jason Mraz
"Viva la Vida" Coldplay
"Just Dance" Lady Gaga & Colby O'Donis
"Low" Flo Rida
"Love Story" Taylor Swift
"Bleeding Love" Leona Lewis
"TiK ToK" Ke$ha
"Disturbia" Rihanna
"So What" Pink

To answer what these have in common, you could classify two different groups: dance-skewing pop and safe, sing-along adult top 40/adult contemporary tracks that will one day be our "oldies." We're looking at you, Mr. A-Z.

And I'm not going to argue that Taylor Swift is country. I'm just not.

So, who buys singles anymore, compared to who buys albums anymore?

The top of the Billboard 200 is frequently rife with country sets, veteran pop and rock acts and the occastional, solo pop female artists and the occasional superstar urban act. It's evident that folks like your mom are still purchasing albums (ex. Susan Boyle, Josh Groban), but your little cousin who has disposable income and spare time jumps on Disney Channel heroes and radio acts.

These are just generalizations, of course, but what of the digital market? Who buys their music still, and who buys singles, these singles, en masse? Looking at this list, it seems obvious: girls and women. Why do you think these songs are the best-selling on iTunes?

While you're at it, iTunes is threatening to award you with a $10,000 iTunes gift certificate if you buy one of the top-sellers and become No. 10,000,000,000. (Here's a hint, though: read the fine print. You don't actually have to purchase to win.)

Follow HitFix’s Katie Hasty on Twitter for more music and movie news at /katieaprincess.