Digital music sales are expected to reach record-breaking numbers in 2012, according to data from a Nielsen study published today.

The previous year held some important milestones for the music business, with a record 1.3 billion digital songs sold and over 100 million digital albums. Nielsen’s study shows that album sales are already up 15 percent compared to the same period last year. Also, U.S. consumers have reached the 1 billion song sales mark. If sales continue at their current rate, 2012 could become the best financial year ever for digital music sales.

“As we look ahead, it’s clear that digital music purchases — and consumption through streaming sources — will continue to grow, and that consumers’ appetites for digital music will change at the speed of technology,” said Nielsen SVP of Client Development David Bakula in the study. “These trends will no doubt continue to shape the way music is discovered, marketed, consumed, and sold.”

As for what’s causing the continued uptick in digital sales year-over year, there are a few explanations. The most obvious reason is that consumers no longer care about the old physical formats, which are much less convenient to both obtain and use across multiple devices. The second and biggest reason is the growing number of people using Internet-connected mobile devices — with an emphasis on devices, plural.

People not only have a smartphone but also a tablet and a laptop/desktop. All of these provide access to at least one digital media storefront. Both Google and Amazon now have their own branded tablet device and have focused on growing their own digital media sales via and the Google Play Store. Also, Samsung, maker of several top-selling mobile devices, is boosting its efforts in the digital media space, having acquired digital media startup mSpot for a rumored $8 million earlier this year. And since prices aren’t extremely competitive between the major digital stores just yet, it’s likely that being able to buy digital media on any device is what’s maintaining this steady growth.

Graphic via Nielsen