China saw almost 90,000 such "mass incidents" of riots, protests, mass petitions and other acts of unrest in 2009, according to a 2011 study by two scholars from Nankai University in north China. Some estimates go even higher.
That is an increase from 2007, when China had over 80,000 mass incidents, up from over 60,000 in 2006, according to an earlier report from the Chinese Academy of Social Sciences.
Over China's multi-millennial history, keeping the nation from falling apart has often proved impossible. Thus, internal unrest is a major concern of the self-perpetuating oligarchy that rules China.
As we quoted in a blog post four days ago, China is the only major country in the world whose police budget is greater than its military budget. Ipso facto, the greatest threat to the People's Republic of China comes from its own citizens.