During the early years, North Korea was ahead of its southern neighbor economically; most likely due to Soviet and Chinese aid. Kim installed a centrally-planned Soviet-style command economy. The means of production was controlled by the government and food prices were fixed instead of being allowed to rise and fall like in a market system. Kim Il Sung formally became leader of North Korea with the establishment of the constitution of the DPRK in 1972 which identified him as President of the republic.