Answer: Communist.
Explanation: An economic system that are characterized by government control of economic decision making process are considered to be communism. Communism is a political and economic doctrine that aims to replace private property and a profit-based economy with public ownership and communal control of the major means of production and the natural resources of a society. Communism is a political, economic ideology whose ultimate aim is the establishment of a communist society, namely a socioeconomic order structured upon the ideas of common ownership of the means of production and the absence of social classes, money and the state.
Surely it would decrease as the population gets bigger as there is less to go around and then people would change to other means of energy without coal