In 2009, the American version of "Dragons' Den", "Shark Tank", began, and "Shark Tank" executive producer Mark Burnett invited two of the CBC "Dragons' Den" investors, O'Leary and Robert Herjavec, to appear on the show. Both have remained with "Shark Tank" since the beginning. For several years, they appeared on both shows, although Herjavec left "Dragons' Den" in 2012, and O'Leary left in 2014. "Shark Tank" became a ratings hit, averaging 9 million viewers per episode at its peak in the 2014–15 season. It has also been a critical favourite, winning the Primetime Emmy Award for Outstanding Structured Reality Program three times.