Market economies have existed under many forms of government and in many different times, places and cultures. Modern capitalist societies—marked by a universalization of money-based social relations, a consistently large and system-wide class of workers who must work for wages (the proletariat) and a capitalist class which owns the means of production—developed in Western Europe in a process that led to the Industrial Revolution. Capitalist systems with varying degrees of direct government intervention have since become dominant in the Western world and continue to spread. Capitalism has been shown to be strongly correlated with economic growth.