instruction:
This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.
question:
Passage: 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: How much of Iran's 33k megawatt installed capacity was based on oil? 
answer:
18%


question:
Passage: In recent years, the city has experienced steady population growth, and has been faced with the issue of accommodating more residents. In 2006, after growing by 4,000 citizens per year for the previous 16 years, regional planners expected the population of Seattle to grow by 200,000 people by 2040. However, former mayor Greg Nickels supported plans that would increase the population by 60%, or 350,000 people, by 2040 and worked on ways to accommodate this growth while keeping Seattle's single-family housing zoning laws. The Seattle City Council later voted to relax height limits on buildings in the greater part of Downtown, partly with the aim to increase residential density in the city centre. As a sign of increasing inner-city growth, the downtown population crested to over 60,000 in 2009, up 77% since 1990. Question: How much increase in population has the inner Seattle city had since 1990?
answer:
77%


question:
Passage: Nigeria is often referred to as the "Giant of Africa", owing to its large population and economy. With approximately 182 million inhabitants, Nigeria is the most populous country in Africa and the seventh most populous country in the world. Nigeria has one of the largest populations of youth in the world. The country is viewed as a multinational state, as it is inhabited by over 500 ethnic groups, of which the three largest are the Hausa, Igbo and Yoruba; these ethnic groups speak over 500 different languages, and are identified with wide variety of cultures. The official language is English. Nigeria is divided roughly in half between Christians, who live mostly in the southern part of the country, and Muslims in the northern part. A minority of the population practise religions indigenous to Nigeria, such as those native to Igbo and Yoruba peoples. Question: What is Nigeria's official language?
answer:

English