According to Symantec’s research, nearly 30 percent of all malicious attacks came from China — with 21.3 percent from Shaoxing alone. Runner-up to the crown was Taipei, at 16.5 percent, with London taking the bronze at 14.8 percent.
On a national scale, China trumped all, followed by Romania, with 21.1 percent of attempted attacks, and the United States, with 13.8 percent.
Symantec MessageLabs : http://www.messagelabs.com/resources/press/47235
ZDNet : http://blogs.zdnet.com/BTL/?p=32452