 It is also one of the world's top ten centres of commerce in terms of global financial flow, generating 6.16% of India's GDP, and accounting for 25% of industrial output, 70% of maritime trade in India (Mumbai Port Trust and JNPT), and 70% of capital transactions to India's economy.Mumbai has the eighth-highest number of billionaires of any city in the world, and Mumbai's billionaires had the highest average wealth of any city in the world in 2008.The city houses important financial institutions and the corporate headquarters of numerous Indian companies and multinational corporations.