The Chinese Export Commodities Fair is held ______.

The Chinese Export Commodities Fair is held twice a year in the city of Guangzhou. It is also known as the Guangzhou Fair: The spring session of the Fair lasts from April 15 to May 5 and the autumn session from October 15 to November 5.
   Tens of thousands of foreign businessmen come to the Fair from all over the world. They are attracted by the various kinds of goods on display. The Fair itself is a mirror of China’s economy. Chinese primary commodities, such as silk, pork, tea, coal and crude oil sell well on world markets. Light industrial and textile products, including garments, and machinery items are also well received in many countries.
   At the Fair, foreign businessmen have negotiations with Chinese exporters.  A lot of contracts are signed.  Foreign merchants say that the Chinese export goods are good in quality and reasonable in price.
   The open - door policy of China makes the Guangzhou Fair ever more colorful and successful.  Orders based on buyers’ designs and different modes of payment are acceptable. Changes like these are welcomed by foreign friends.
   The Chinese export corporations are doing their best to improve the quality, designs, packing and delivery of the export goods in order to make them more competitive on the overseas markets.
11: How many times is the Chinese Export Commodities Fair held a year?