May 9 - China's periodical sector has undergone a drastic development and the total number of periodicals has reached 9,468 by the end of April, a senior official said on Monday.In 2006, China published 2.85 billion copies of periodicals with a total set price of around 14 billion yuan (about 1.8 billion U.S. dollars), according to Li Dongdong, deputy director of the General Administration of Press and Publication."The development of China's periodical sector is shown not only through copy numbers, but also through its role as a cultural industry," said Li. "It has grown to be a industry with annual production value of more than 17 billion yuan (about 2.2 billion U.S. dollars)."The annual advertisement income of China's magazines has reached 3 billion yuan (about 0.4 billion U.S. dollars), developing at double-digit percentages for many years on end, Li said.The 36th World Magazine Congress will be held in Beijing from May 13 to 15. The Congress, initiated by the International Federation of the Periodical Press, founded in 1925, is held every two years.