Source: http://bits.blogs.nytimes.com/2013/11/19...

One striking thing about the map: Bitcoin is increasingly a Chinese craze. Even at the height of the American and European trading days, when it’s 3 a.m. in China, Chinese transactions far outstrip activity in euros. The United States dollar transactions are still more popular than Chinese at that time, with about twice as many transactions. China was barely involved in bitcoin a year ago, however. The Chinese presence can also strengthen when it is daytime in China and night in the United States.

“You can watch China and the U.S. play Ping-Pong on this,” said Andrew Hodel, who built the site. “You see the psychology, as the bitcoin goes over a threshold number in dollars or yuan.”