For 15 years in a row, the number of applicants for H-1B work visas has far exceeded the program's cap of 85,000 available visas. The H-1B program, which allows US companies to bring in foreign workers in specialized fields like math, science and engineering, has long been a magnet for controversy. Tech companies say they need the visas to get scarce talent, while labor advocates contend that it allows companies to hire cheaper foreign workers instead of Americans.

Amazon, Microsoft, and Google are just a few of the tech giants that rely on the H-1B visa to snatch up coveted tech talent, and as this chart by Statista shows, this trend has only increased in recent years. Among five prominent tech companies, each saw an increase in approved applications for H-1B working visas from 2016 to 2017, with Amazon taking up the largest share of applications.