The latest AppAnnie statistics once again highlight the biggest app market trend of the past year: Google (GOOG) has started showing spectacular mobile app revenue growth. According to AppAnnie, Google Play app revenue soared by about 100%, while iOS app revenue grew about 20% between the third and fourth quarters last year. Doubling sales over a three-month period is an impressive performance. Total app revenue from the iOS camp is still nearly four times the amount of revenue that Google Play generates; but if the current growth trends persist, that gap is going to narrow very soon.

Apple (AAPL) did have a robust Christmas period. In December, iOS app store revenue grew 35% over November whereas a year earlier the month-on-month growth was 25%. But Google Play app revenue surged between July and November, while iOS app revenue was surprisingly sluggish during the iPhone 5 launch period. One possible explanation is that Android camp may now be grabbing the lion’s share of new smartphone buyers who start building their app libraries from the scratch. Many of the iPhone 5 buyers already owned an older iPhone model and simply moved their existing app portfolios to the new device.

AppAnnie has a fascinating chart, pictured above, which demonstrates how the explosive growth of Google Play in Japan and South Korea is now driving the global sales expansion of the ecosystem. While this is happening, Asian game developers are getting an effective stranglehold on the Google Play top-10 revenue chart — nine out of the 10 biggest Android app revenue generators were Japanese or Korean in December.

This is food for thought for Western app developers. As Google Play narrows the revenue gap with iOS, most American and European developers are still tightly focused on iPhone and iPad as their primary hardware platforms. Android versions of most popular games often arrive more than six months after the Apple versions and often don’t receive extra levels or features. Cracking the lucrative Korean and Japanese app markets will probably require more attention for Android development.