Music sales continued their free-fall during the first six months of 2014, as both albums and digital downloads again showed double-digit losses.

According to Nielsen SoundScan data released Wednesday for the year to date through June 29, total album sales in all formats plunged nearly 15%, with sales of almost 121 million, versus 142 million sold in the first six months of 2013.

To put the steepness of the decline in perspective: Just 18 months ago, Adele’s Grammy-winning “21” — the bestselling album of 2011 and 2012 — finished the latter year with sales in excess of 10 million. It is conceivable that such a phenomenon will not be seen in the industry again.

Digital track sales dropped 13% to 593.6 million, in comparison to 682.2 million moved in the same period last year.

On-demand streaming continued to boom, soaring 42% to almost 70.3 million streams (compared to 49.5 million in the same period last year). However, revenues derived from streaming are a fraction of those derived from physical and digital album sales on a per-unit basis.

Once again, vinyl albums showed a potent gain, up more than 40% to 4 million units (compared to 2.9 million in the first half of 2013), though the format remains a sliver of the industry’s overall business. Jack White’s “Lazaretto,” which was issued in a special holographic LP edition, was the bestselling title at 49,000 units.

In a statement, Nielsen senior vp David Bakula said the lifts in streaming and LP sales “shows interest in buying and consuming music continues to be robust, with two very distinct segments of the industry expanding substantially.”

So far this year, the bestselling album title – and the only one to sell more than a million units – is Disney’s soundtrack for the hit animated picture “Frozen,” which has moved nearly 2.7 million units. Cumulatively, the late-2013 release has sold just over 3 million; it is situated at No. 5 on the top albums chart released Wednesday.

“Frozen” was succeeded among the year’s bestsellers by Beyonce’s self-titled collection (702,000), Eric Church’s “The Outsiders” (642,000), Lorde’s “Pure Heroine” (641,000), and Coldplay’s “Ghost Stories” (589,000). “Beyonce,” a surprise digital release in December, and Lorde’s title, the teen singer’s Grammy-nominated debut, were released in 2013.

Among digital songs, Pharrell Williams’ ubiquitous “Happy” — heard on the “Despicable Me 2” soundtrack” — was the top seller, moving 5.6 million for the year. It was followed by Katy Perry’s “Dark Horse” (4 million), John Legend’s “All of Me” (3.8 million), Jason Derulo’s “Talk Dirty” (3.6 million) and “Frozen” vocal star Idina Menzel’s soundtrack hit “Let It Go” (2.8 million).

Perry’s “Dark Horse” was the most-streamed song, with 188 million audio and video spins to its credit. It was succeeded by Legend’s “All of Me” (145 million), Derulo’s “Talk Dirty” (142 million), Williams’ “Happy” (135 million) and Menzel’s “Let It Go” (129 million).

“Happy” was the most-played song on terrestrial radio stations tracked by SoundScan’s Broadcast Data Systems unit, with 571,000 spins.