Most North Koreans now rely on open-air markets or other forms of commerce to make a living. According to South Korean think tanks, the development of such markets would allow North Korea to merge with South Korea's free market economy five years after reunification. The emergence of open-air markets has reduced North Koreans' dependence on unreliable food rations. A study of North Korean defectors conducted by Kim Byung-yeon at the Institute for Peace and Unification Studies at Seoul National University showed that more than 74% of defectors had experience selling goods in open-air markets. Furthermore, these defectors derived 70-80% of their income from this unofficial economic activity and spent 80-90% buying goods in informal markets rather than state-run stores. The emerging market economy in North Korea is now an irreversible trend and reported to be more developed than in other former socialist countries such as East Germany and China.