Please answer the following question: Read the following article and select the best answer. Article: Have you ever wondered what you will be when you grow up? Perhaps you have thought of becoming an engineer or an environmentalist. Here's good news: you can combine all of these career goals by designing, building and operating a solar-powered house. That is what students from 20 universities did as they competed in the U.S. Department of Energy 2009 Solar Decathlon . Like a game show where teams compete against each other, the Solar Decathlon's student teams competed against each other in ten separate events to see who could build the best solar-powered house. The team from Germany took the top honor. The contest is held on the National Mall in Washington D.C., and is open to the public. In order to win, the Decathlon's teams have to successfully host a dinner party, do the laundry, run the dishwasher, and maintain a comfortable temperature in their solar-powered houses. They also have to make their houses look attractive. Team Germany's winning "Cube House" produced a surplus of power, even during three days of rain. This is the fourth time the Solar Decathlon has been held. The houses keep getting better and better. "The Department of Energy does research on solar and building technologies. In the 1990s, we were seeking expertise to help design houses that would integrate solar systems in a reliable way. I came up with the idea of having a competition to challenge students at architecture and engineering schools to design solar-powered houses from the ground up. I thought that having a competition would motivate these students to be creative. The new generation of our country should be innovative . They may come up with solutions that would help our country," said Richard J. King, the Decathlon's Director. Question: What do we know about the Solar Decathlon from the text? - The participated teams are separated from the outside world during the competition. - The house designed by the German team will be adopted by the Department of Energy. - The competition had been held three times before 2009. - It includes students from twenty countries around the world.
Answer:
The competition had been held three times before 2009.