Mobile gaming revenues are expected to grow by 16.5 percent this year, totaling $3.04 billion. The figure - which includes downloads and in-app purchases - highlights the stagnant state of eBook and music downloads according to a new report from eMarketer.

As you might expect, the popularity of the freemium business model is really driving in-app purchases. In 2015, in-app purchases are expected to account for 59.8 percent of all mobile game revenues. Doing the math, that works out to a total of $1.82 billion.

All factors considered, mobile games are expected to account for nearly a third of the entire US mobile content market in 2015. eBook downloads will decline to fill 43.3 percent of mobile revenues, video downloads will account for 8.6 percent and music downloads will drop to 5.6 percent. The latter two illustrate the growing popularity of video and music streaming services like Netflix and Spotify, respectively.

Looking at the bigger picture, the US mobile content market is forecasted to rake in $9.82 billion this year - an increase of more than 10 percent compared to last year. With that kind of money floating around, it's no wonder that some app developers are now making more money than Hollywood stars.

As for the future, eMarketer notes that smartphone and tablet ownership in the US isn't yet at saturation although the days of explosive growth are certainly in the rear view mirror.