In its new Mobile Gaming 2014 report, market researcher The NPD Group shows just how popular mobile gaming has become in the US.

The report found that on average, time spent playing games on a device (smartphone, tablet, iPod Touch) has increased 57% since 2012. Gamers are spending more than two hours a day playing, versus one hour and 20 minutes in 2012.

When it comes to age, kids are playing a large role in driving up those numbers. The study found the average number of minutes per session peaked in the tween years, falling through the teen and early adult years.

Meanwhile kids ages two to 12 are spending the greatest proportion of their device time on gaming versus other activities. This age group is also playing more games (an average of five), as well as more games that were paid for (an average of three). The amount of money spent over the past 30 days on new games and in-game purchases, was one of the highest, second only to mobile gamers in the 25 to 44 age group.

Regardless of the number of devices used to play games, mobile devices see the greatest amount of play time. The report also pointed to the growth of the tablet market, as well as continued improvement of tablet technology, which has seen these devices become central to the mobile gaming story.

Not only are tablets being used to game with the most, but tablet gamers are also more likely to pay for games and spend more money than those using other mobile platforms.

While time spent gaming on mobile devices is increasing, the news wasn’t all bad for traditional gaming devices. The report found that console and computer gamers are playing just as much as they were one year ago.