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iOS still earns developers four times as much revenue as Android, but Google is closing the gap, according to App Annie, a mobile apps analytics company.

iOS revenues have grown just 13 percent in 2012, while Google Play revenues have more than tripled. Game publishers have seen the most revenue growth on Google Play.

On both platforms, LINE was among the most lucrative non-gaming apps.

Japan edged out the United States in September as the largest revenue generator on Google Play, according to App Annie. No country has ever outclassed the United States before. In the App Store platform, the U.S. remains top dog.