Although China accounts for about 5 percent of worldwide ticket sales, certain types of movies generate far more than that, according to a study by Robert Cain, a producer and veteran studio consultant on China. In an article for his China Film Biz blog, Cain observes that in 2011, the Chinese box office accounted for 15.4 percent of international sales for Sony's Battle Los Angeles (retitled in China World Invasion Battle Los Angeles ) . It accounted for 14.8 percent of international sales for Transformers Dark of the Moon ( Transformers 3 ) and 14 percent for Kung Fu Panda 2 . It also overperformed for such films as I Am Number Four, Real Steel, Skyline, and The Green Hornet. Cain refers to Battle Los Angeles as "the prototypical over-indexer," noting that almost every U.S.-made film that performed strongly in China this year was either a sci-fi or an action film or both. The No. 2 film on the list, Transformers 3 , accounted for $165 million of the film's global total of $1,1 billion. (Chinese receipts represented 21 percent of its foreign total of $771 million.) The only exception to the sci-fi/action rule, Cain notes, was Kung Fu Panda 2 , and in that case, he said, it is "fairly obvious" why it performed so well. What defines a movie that does especially well in China is its reliance on spectacle rather than dialogue and "a level of effects and production value that can't be matched by home-grown films," and they target 12-25 year olds. Another factor producers of such films should consider, Cain notes, is the import quota, which allows only 20 foreign films to be shown in the country each year. A filmmaker planning to make a sci-fi or action film, he says, should think about the possibility of doing it as a co-production, which he notes, can return as much as 40 percent of Chinese box-office revenue versus just 13-15 percent for quota films. "The extra revenue could make it worth the extra effort of working with Chinese partners," Cain concludes.