China will surpass the U.S. in iOS and Android device install base by Q1 2013′s end, predicts mobile app monetization company Flurry.

The company’s prediction comes from a new report released today, focusing on which countries have the largest active iOS and Android device install base, which countries are showing the fastest growth and how app usage is shifting across the globe. Flurry believes only a holiday season that will spike the U.S. install base would prevent China from passing up the U.S. in a shorter amount of time. 

The top two countries by active iOS and Android install base as of Oct. 2012 are the U.S. with 181 million active devices and China with 167 million. Both countries have a markedly higher install base by at least five times more than other countries including the U.K., Japan, South Korea, Germany, France, Canada, Brazil and Spain. Since Oct. 2011, the U.S. added 55 million devices to its install base while China added 125 million, a figure that is larger than the current install base for the U.K., Japan and South Korea combined.

From Oct. 2011 to Oct. 2012, China had the most growth in active devices with an increase of 293 percent, which Flurry attributed to the combination of the country’s population and growing middle class. Since Flurry’s prior international growth report, a new set of countries are in the top 10 including Colombia, Ukraine, Venezuela and the Philippines. The countries selected for the chart had a minimum of half a million active devices as of Oct. 2011.

The report also looked at the worldwide distribution of iOS and Android app usage, showing a significant drop in app usage for the U.S.

In Oct. 2011, 48 percent of app usage was in the U.S., but a year later dropped to 29 percent. The rest of the top 10 (ranks 2-9) grew their usage from 27 percent to 39 percent in 12 months. The rest of the world grew from 25 percent to 32 percent. As it stands, 71 percent of app usage take place outside the U.S., according to Flurry.

Flurry pulled data for this report from more than 250,000 apps that it tracks, running on more than 750 million devices worldwide. The company says it can detect 90 percent of all active iOS and Android devices around the world in a given month.