context: In 2004, a large share of natural gas reserves in Iran were untapped. The addition of new hydroelectric stations and the streamlining of conventional coal and oil-fired stations increased installed capacity to 33,000 megawatts. Of that amount, about 75% was based on natural gas, 18% on oil, and 7% on hydroelectric power. In 2004, Iran opened its first wind-powered and geothermal plants, and the first solar thermal plant is to come online in 2009. Iran is the third country in the world to have developed GTL technology.
question: ఇరాన్ యొక్క 33 కె మెగావాట్ల వ్యవస్థాపిత సామర్థ్యంలో ఎంత చమురు ఆధారపడి ఉంది?
answers: 18%