When the audio cassette celebrated its 50th anniversary a few years back, many (myself included) assumed that would be the last we'd hear of the antiqued recording format. Well, you know what they say about making an assumption.

As it turns out, cassette tapes didn't ride off into retirement alongside the VCR. Instead, sales of cassette albums shot up 74 percent in 2016. Wait, what?

Sales of cassette-based albums climbed to 129,000 units in 2016, up from just 74,000 a year earlier. That's a miniscule number when you consider album sales in general totaled 200.8 million but it's fascinating nevertheless, especially to those that didn't realize cassette tapes were still in production.

The sudden growth, as Billboard highlights, can be attributed to a handful of specialty releases such as Justin Bieber's Purpose album and Beauty Behind the Madness by The Weekend. The publication notes that reissues of classics like Prince and the Revolution's Purple Rain and The Slim Shady LP from Eminem also contributed substantially. The top spot, however, was held by Guardians of the Galaxy: Awesome Mix Vol. 1 soundtrack with 4,000 units sold per year in 2015 and 2016.

Billboard says most albums (43 percent) were sold via the Internet and web-based, direct-to-consumer settings. Independent retail stores accounted for 33 percent of tape sales while non-traditional music stores were responsible for 21 percent of sales. The remaining market share was scooped up by major chains.

Vinyl's resurgence, meanwhile, continued in 2016 with sales totaling 13.1 million, a 10 percent increase compared to 2015.

Image courtesy Zen Inside Zen