In the 1970s, they came from Iran, riding the wave of the oil boom. Then in the first decade of the second millennium, they came from India, filling up graduate programs in business and science. Now, it’s Chinese students who comprise the largest group of international pupils in the United States, buoyed by a growing Chinese middle class that’s willing to pay top dollar for their children’s educations. According to an annual report by the Institute of International Education (IIE), in the 2014-2015 academic year more than 304,000 Chinese students were enrolled in U.S. colleges and universities, an almost five-fold increase from just a decade earlier.