Istanbul is ranked 29th among the world’s urban areas. Istanbul’s economy has been one of the fastest growing among OECD metro-regions. According to Foreign Policy and the McKinsey Global Institute, Istanbul will register the 14th-highest absolute GDP growth among world cities by 2025. Istanbul is responsible for 27 percent of Turkey’s GDP, with 20 percent of the country’s industrial labor force residing in the city. Its GDP per capita and productivity are greater than their national averages by 70 percent and 50 percent, respectively, owing in part to the focus on high-value-added activities. With its high population and significant contribution to the Turkish economy, Istanbul is responsible for two-fifths of the nation’s tax revenue. That includes the taxes of thirty-seven billionaires based in Istanbul, the fifth-highest number among cities around the world. Istanbul is home to Borsa Istanbul, the sole exchange entity of Turkey, which combined the former Istanbul Stock Exchange, the Istanbul Gold Exchange, and the Derivatives Exchange of Turkey. As the only sea route between the oil-rich Black Sea and the Mediterranean, the Bosphorus is one of the busiest waterways in the world; more than 200 million tonnes of oil pass through the strait each year, and the traffic on the Bosphorus is three times that on the Suez Canal. Istanbul is an increasingly popular tourist destination; it the world’s fifth most-visited city.