Chicago is an international hub for finance, commerce, industry, technology, telecommunications, and transportation. It was the site of the creation of the first standardized futures contracts at the Chicago Board of Trade, which today is the largest and most diverse derivatives market in the world, generating 20% of all volume in commodities and financial futures. O'Hare International Airport is the one of the busiest airports in the world, and the region also has the largest number of U. S. highways and greatest amount of railroad freight. In 2012, Chicago was listed as an alpha global city by the Globalization and World Cities Research Network, and it ranked seventh in the entire world in the 2017 Global Cities Index. Chicago has one of the highest gross metropolitan products in the world—generating over $679. 69 billion in 2017. In addition, it has one of the world's most diversified and balanced economies, not being dependent on any one industry, with no single industry employing more than 14% of the workforce.