In that category, Indian workers are still on top with 47 percent of the visas, or 8,103, followed by China with 19.5 percent; Canada 3.4 percent; Korea 2.4 percent; Mexico, 2.2 percent; and Taiwan and Iran with 2.2 percent each, the data shows. The hiring of H-1B workers has raised concerns after it was reported that some U.S. companies were using IT outsourcing companies to replace their IT shops, leaving American IT professionals out of work. Some of the U.S. workers had to train their replacements, who worked for IT outsourcing companies. The issue has led to lawsuits by laid-off IT workers and prompted calls in Congress for an investigation into the use of H-1B visas. Lawyers for the outsourcing companies have said there is no requirement for a foreign company doing business in the U.S. to employ U.S. workers. The companies are only required to comply with immigration laws.