PS4 was the best-selling console for December and all of 2015 in the U.S.

2015's overall video game sales may have come in flat compared to 2014, but don't blame current-gen systems (Xbox One, PS4, and Wii U) for the overall sales decrease of less than 1 percent.

According to the NPD Group's report (which tracks sales in the United States), the 6 percent decrease in sales in December 2015 versus December 2014 was driven by a 71 percent drop in 7th-gen hardware and a 32 percent decrease in portable hardware, despite a 4 percent increase in 8th generation spending.

In fact, December 2015 was the best month ever for total hardware unit sales for 8th generation consoles (Xbox One, PS4, and Wii U), beating last month's record.

More specifically, December 2015 marked the best month to date of PS4 and Xbox One sales, although Sony's system was once again the best-selling console for the month, and for the year in total.

"As we reflect on an amazing year, we want to thank fans and partners for making PlayStation 4 the top selling console in December and in 2015," a Sony spokesperson commented. "PS4 also had the strongest third-party software sales in 2015 in the US, according to NPD."

NPD Group noted that a growth over 2014 for both consoles makes 2015 the best year for PS4 and Xbox One hardware sales.

After 26 months of sales, the combined cumulative sales of Xbox One and PS4 exceeds the 26 month total of the PS3 and Xbox 360 by 47 percent. Breaking it down month by month, NPD Group's Liam Callahan noted, "The lead from the prior generation has expanded due to the strong PS4 and Xbox One 2015 holiday, going from 38 percent by the end of October, growing to 47 percent by the end of November, and maintaining 47 percent higher sales by the end of December.”

While NPD Group tracks only U.S. sales, it can be assumed the PS4 is outselling the Xbox One on a global level as well. The latest official figure from Sony has PlayStation 4 consoles sales surpassing 35.9 million units globally as of January 3, 2016. Microsoft hasn't announced official Xbox One sales, but a recent report suggests "at least" 18 million consoles sold.