The average number of hours spent per week on online gaming is up 10 percent, to 8 hours a week, according to the results of a study released by the NPD Group today.

"While the percentage of the population that reports playing games has declined slightly, this study details other metrics which point to both stability and growth in both online and offline gaming," said Anita Frazier, industry analyst, The NPD Group.

The PC remains the most-used system for online gaming, according to the report, with 85 percent of online gamers reporting using a PC for online gaming activities.