Quick: which nation on earth uses more smartphones than any other? The United States? India? Japan?

As of today, none of the above, according to new research by Strategy Analytics (News - Alert). That honor now belongs to the world's most populous country, China, which took the lead in the third quarter of this year.

The report notes that shipments of smartphones in China grew 58 percent in the third quarter alone – up from 24 million units in the previous quarter. The U.S., on the other hand, is trending downward: smartphone shipments actually dropped seven percent – to 23 million units – in the same quarter, according to the Wall Street Journal.

Aggressive growth in China is attributed to strong subsidizing by Chinese telecom interests of high-end smartphones such as Apple's iPhone (News - Alert), according to Strategy Analytics analyst Tom Kang. In addition, growth can be attributed to the growing availability of lower-cost smartphone models running Google's Android (News - Alert) mobile operating system. 

So which smartphones are the Chinese using? According to the Strategy Analytics report, Nokia is still number one in China with 29 percent market share, but it may not be for long. Both Samsung and Apple are rapidly catching up, with new potential for Apple that will potentially launch it into the top spot.

If China Telecom (News - Alert) launches a CDMA iPhone 4S early next year, as planned, then Apple's Chinese market share could overtake all other manufacturers. In addition, both HTC and Sony Ericsson (News - Alert) gained market share in China this quarter thanks to their new Android handsets, which were major sellers in eastern and southern Chinese cities.