Trusted game industry sources who receive NPD figures have once again given us some insight into how the Xbox is doing sales-wise in the US.

NPD Group research retail sales in the US, offering Sony and Microsoft the opportunity to say who "won" the sales race for each month. The actual figures are a closely guarded secret, until now!

For the month of December, Xbox sold 1,511,000 units across both its Xbox One and Xbox One S consoles, which puts Xbox sales up 10% year-over-year for December. Sony took the sales lead selling 1,568,000 consoles during December, with 238,000 units of its PlayStation 4 Pro edging Microsoft into second place.

Editor's Note: Since NPD figures are not made publicly available the veracity of the numbers reported here may be in question by some readers or even other media outlets. However, as the editor in chief of Windows Central I can vouch for the authenticity of the information presented here without hesitation. - Daniel Rubino

Update: Since this article went live, we received trusted information that over 80% of Microsoft's December sales were of Xbox One S variants.

While Microsoft doesn't offer hard sales figures itself, Redmond did issue a statement to us last week confirming that it had seen year-over-year growth for Xbox, with record-breaking Xbox Live engagement for November and December.

December was the biggest month ever for Xbox One sales in the U.S. and Xbox One was the only eighth generation console with year-over-year growth, according to NPD. In addition, Xbox One was the top-selling console over the second half of 2016, following the announcement of Xbox One S at E3.

In November and December we saw Xbox Live engagement reach an all-time high of 3.9 billion hours, up 23 percent compared to 2015 driven by fan excitement for the greatest games lineup. Looking ahead, we expect 2017 to be a special year for gamers thanks to the upcoming launch of the most powerful console ever in Project Scorpio and a terrific portfolio of new games with Xbox Live support on Xbox One, Windows 10 or both. – Mike Nichols, Corporate Vice President, Xbox Marketing, Microsoft

The sales of the PlayStation 4 Pro are particularly interesting considering Microsoft will launch a similar Xbox One "upgrade" console towards the end of 2017, Project Scorpio. There are only a few dozen titles utilizing the PlayStation 4 Pro's specs to offer improved visuals as of writing, but by the time Project Scorpio comes out, there will be much, much more. Microsoft will no doubt be looking to create a compelling lineup of true 4K games to match when Scorpio lands during the holiday season of 2017, and thanks to UWP, it may just achieve its aims.

Microsoft is leveraging Windows 10 and UWP to craft games that scale across the ecosystem, with a target of true 4K resolution for powerful PCs and Project Scorpio. While we haven't seen a great deal of traction when it comes to large third-party game publishers supporting UWP and the Windows 10 Store, the tide is turning, with Resident Evil 7 and Call of Duty: Infinite Warfare already on board.

One thing is for certain — the figures show that the industry is incredibly healthy, with both companies posting strong figures. It will be interesting to see if Microsoft can edge back into the forefront in the months between now, and when Project Scorpio launches proper.