The breakdown sees gaming most popular among ages 9-11, a demographic that accounts for 12.4 million, and least popular between ages 2-5 at 9.7 million, with 51% of the total "kid gamer" market playing games online.

Meanwhile, the 12-14 demographic spent the most time playing games at 10.6 hours per week, with males aged 9-14 being "more inclined" to play games online. Along with females, teens between 15-17 were the two groups "most likely to report spending less time gaming and playing online this year versus last year."

"The decline in teen usage of video games is likely due to diversifying, maturing interests, which translates into stiffer competition," postulated analyst Anita Frazier, adding that the data suggests parent-imposed time limits, more school work, activities, and other forms of entertainment "may be contributing to this dip in older teen engagement."

As for what they're gaming on, the report claims that the children used an average of 2.5 dedicated gaming systems or devices, with those between 9 and 12 using "about 3 system/devices on average." Non-traditional gaming devices, like cell phones and portable media players, were more popular among the older groups.

Along with the report, The NPD Group provided an explanation of its methodology:

Methodology

The report is based on online survey responses from over 5,000 members of NPD's online consumer panel ages 2-17 (respondents age 2-12 were captured via surrogate reporting). Respondents had to report that they currently, personally play video games on a PC/Mac, video game system or device used for gaming. Final survey data was weighted to represent the U.S. population of individuals age 2-17. The survey data is weighted to represent the U.S. population of individuals ages 2 and older. Fieldwork was conducted from September 10-17, 2009.