I cover energy here at CNBC and here's what you need to know about Iran's role in the global oil markets. Iran pumps around 3.4% million barrels per day. By comparison, Saudi Arabia almost triples that at 9.5% million barrels and the U.S. pumps even more, about 13.5% million barrels per day.On top of that, existing sanctions due to disputes around Iran's nuclear program means that Iran's exports can't be sold on the open market. China has essentially become the lone buyer of Iranian barrels. What the sancti ...