Dubai is the largest and most populous city in the United Arab Emirates. The city of Dubai is located on the emirates northern coastline and heads the Dubai-Sharjah-Ajman metropolitan area. Dubai will host World Expo 2020. Dubai emerged as a global city and business hub of the Middle East. It is also a major transport hub for passengers and cargo. By the 1960s, Dubais economy was based on revenues from trade and, to a smaller extent, oil exploration concessions, but oil was not discovered until 1966. Oil revenue first started to flow in 1969. Dubais oil revenue helped accelerate the early development of the city, but its reserves are limited and production levels are low: today, less than 5% of the emirates revenue comes from oil. The emirates Western-style model of business drives its economy with the main revenues now coming from tourism, aviation, real estate, and financial services. but the emirates economy has made a return to growth, with a projected 2015 budget surplus. , Dubai was the 22nd most expensive city in the world and the most expensive city in the Middle East. In 2014, Dubais hotel rooms were rated as the second most expensive in the world, after Geneva. Dubai was rated as one of the best places to live in the Middle East by U.S. global consulting firm Mercer.