China has 668 million Internet users, accounting for 48.8 percent of the country's total population, as e-commerce boomed in the world's second-largest economy, authorities said. A total of 18.94 million new users -- more than the population of Chile -- were added in the first six months of this year, the semi-official China Internet Network Information Center (CNNIC) said in its biannual report. "Mobile business applications grew rapidly as Internet applications developed in an experience-improving and economics-relevant way," CNNIC said in a statement. China, which already had more web users than any other country in the world, defines its online population as those who have used the Internet at least once in the last six months. The number of mobile payment users increased by 26.9 percent from December to 276 million, while those using their cellphone to shop online rose 14.5 percent to 270 million, the statement Wednesday said. In the first half of this year, China's online retail sales soared 39.1 percent from a year ago to exceed 1.6 trillion yuan ($258 billion), previous government data showed. The country's roller-coaster stock market this year saw the number of people using the Internet to trade shares spike, surging 47.4 percent from December to 56.28 million, CNNIC added. The benchmark Shanghai Composite Index has gained around 17 percent since the market bottom of a sudden slump earlier this month.