HAIKOU, Jan. 25 (Xinhua) -- Offshore duty-free shops on the popular resort island of Hainan have made 30.59 billion yuan (about 4.77 billion U.S. dollars) in sales since the program launched in April 2011, the provincial finance bureau announced Thursday.

Official data showed that the two shops, one in the provincial capital of Haikou and the other in the resort city of Sanya, have received more than 9.7 million customers, with per capita consumption of 3,133 yuan.

The State Council gave Hainan permission to run a trial duty-free program on April 20, 2011 to help make the island a world-class tourist destination by 2020.

Without any restrictions on the number of purchases, non-locals are allowed to buy duty-free products worth up to 16,000 yuan a year before they take flights or trains leaving the island.

Travelers can also order online and pick up their goods at the airport or railway station.

The shops have been an important driver for the island's tourism industry, and the average duration of tourist stays has increased by 0.6 days since the program launched.