Between 1978 and 2015, more than 4 million studied internationally; 2.2 million returned

China has the largest number of students studying overseas and they play a key role in the trends of international student mobility, according to a report.

China had a total of 1.26 million students overseas as of 2015, accounting for 25 percent of the world's total number of students studying outside their native country, meaning one in four such students is from China, according to the 2016 Report on the Development of Chinese Students Studying Abroad.