The service sector accounts for 51 percent of the country's GDP. Bangladesh ranks with Pakistan as South Asia's second-largest banking sector. The Dhaka and Chittagong Stock Exchanges are the country's twin financial markets. Bangladesh's telecommunications industry is one of the world's fastest-growing, with 114 million cellphone subscribers in December 2013, and Grameenphone, Banglalink, Robi and BTTB are major companies. Tourism is developing, with the beach resort of Cox's Bazar at the center of the industry. The Sylhet region, home to Bangladesh's tea gardens, also hosts a large number of visitors. The country has three UNESCO World Heritage Sites (the Mosque City, the Buddhist Vihara and the Sundarbans) and five tentative-list sites.