Though it’s easy to believe that the video games industry is relatively recession-proof, the latest numbers from Port Washington, New York-based market researcher The NPD Group have found that its staggering pace of growth in Q2 and Q3 2008 took a hit in the last quarter.

December sales saw a 9% increase from 2007 numbers, with 2008 annual video game sales sitting at a cool US$21.33 billion – still 19% ahead of the previous year’s take, setting a record for total industry sales. NPD toy and video games analyst Anita Frazier notes that December was the first time industry revenue topped US$5 billion in a single month, compared to 1997, when annual revenues were US$5.1 billion.

Unsurprisingly, the Nintendo DS sat at the top of the list for hardware sales in December, also setting a record for any hardware system, moving more than three million units in a single month. Overall 9.95 million DSes were sold last year, coming in second to its bigger console cousin, the Wii, which realized annual unit sales of 10.17 million, both breaking the previous year’s records.

Nintendo reports that the Wii represented 55% of all next-gen home console sales in 2008, while the DS accounted for 72% of all portable system sales from last year.

On the software side, annual sales were up 26% from 2007 to roughly US$11 billion. The top-selling four games of 2008 were also Nintendo titles: Wii Play, Mario Kart Wii, Wii Fit and Super Smash Brothers Brawl. As for the ever-popular Guitar Hero and Rock Band titles, they both sold more units on the Nintendo platforms than any others last year.