Pakistan is a federation of four provinces. Sindh is the south-eastern province and Karachi is its capital. According to pre-census results conducted in 2013, it is the fastest-growing city in the world. It is also Pakistan’s largest city and its only port. Its 2010 population was estimated at 15.4 million while its current population is estimated to have reached over 20 million. Based on these figures, it is further estimated that 9% of Pakistan’s total population and 24% of the country’s urban population, live in Karachi. The city also generates 15% of the national GDP, 25% of the revenues, and 62% of the total income tax. There are also powerful federal landowning interests in the city in the form of the Karachi Port Trust (KPT), Port Qasim, Customs, Civil Aviation Authority (CAA), Railways, and the armed forces and their various industrial and real estate activities.