Dubai is a global city and business hub of the Middle East. It is also a major global transport hub for passengers and cargo. 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 emirate's revenue comes from oil. Dubai's economy now relies on revenues from tourism, aviation, real estate, and financial services.Dubai has attracted world attention through large construction projects and sports events, in particular the world's tallest building, the Burj Khalifa. Dubai has been criticised for human rights violations against the city's largely South Asian and Filipino workforce. As of 2012, Dubai was the most expensive city in the Middle East. In 2014, Dubai's hotel rooms were rated as the second most expensive in the world.