According to a new portable gaming report from mobile analytics company App Annie, global consumer spending on mobile games continues to grow at a remarkable rate as more people migrate to smartphones and tablets. While iOS continues to outpace Android in terms of revenue, Android's greater growth potential might be more appealing to mobile game makers concerned about discoverability in the iOS app store. Of course, the report suggests people are spending more money on mobile games worldwide across both iOS and Android app stores. Total revenue generated from games (excluding ad revenue) in the Google Play store more than doubled between the second quarter of 2013 and the second quarter of 2014, while iOS app store game revenue grew by more than 70 percent in the same period. As you might expect, free-to-play heavyweights Puzzle & Dragons, Candy Crush Saga and Clash of Clans remained the top three earners across both ecosystems. Yet the share of total iOS app store revenue generated by spending on games barely changed at all year-over-year; games still account for roughly 75 percent of global spend in iOS app stores, while on Android that figure saw a moderate increase year-over-year so that games now account for roughly 85 percent of user spending (App Annie's report excludes ad revenue.) That suggests that the remarkable growth in mobile game spending is being driven by new mobile users entering the market, rather than increased demand from current smartphone and tablet owners. And it seems like those newcomers favor Android devices, as App Annie reports that Android's share of the total global smartphone and tablet install base rose by roughly 8 percent year-over-year, at the expense of iOS, Windows Phone, Blackberry and other devices. But iOS continues to outpace Android in terms of app store game revenue worldwide, especially in the United States, where App Annie estimates iOS games generated more than double the revenue of Google Play games.