According to this Gamasutra article, revenue for online games in China was up 71 percent from 2006 to 2007 to $1.7 billion - with 21 percent of that figure coming from casual and "advanced casual" titles.
The numbers come from market research firm Niko Partners' sixth Annual Review & Forecast Report on China's Video Game Industry.
"Disposable income is rising, and people are able to spend a more money on games then they have in the past. The number of games has increased because as it becomes a more popular pasttime, the younger kids join this force, and the older gamers continue to play," said Niko's Lisa Cosmas Hanson.
Infinite numbers and import through the link.