If you never got around to sending the record industry a get well card, you should probably instead use the money on a digital download or three.

Billboard reports that this week's 3.97-million album sales total is the smallest weekly sum since Nielsen SoundScan began tracking data in 1991. It's also the first time since then that weekly sales have fallen below four million.

Last week's top-selling album, Wiz Khalifa's 'Blacc Hollywood,' debuted with 90,000 units sold -- well below the first-week sales of many other top debuts this year and while three other albums debuted in the top 10, they but averaged only 31,000 units moved each. The same week last year, 4.88 million albums were sold. This year, there have only been five weeks with more than 5 million sales and they each happened more than 18 weeks ago.

"I remember when album sales fell under 10 million units and the industry reacted like it was a tragedy," said one record distribution sales executive.

The culprit: online streaming services like Spotify and Pandora. Although some insiders claim revenue from streaming continues to make up for lost digital sales, others aren't so sure.

"This year the bottom fell out of digital sales to a degree that we never anticipated," said one indie distribution executive. "Which is why many companies are not meeting this year's revenue projections."