according to paul reynolds, founder of the global entrepreneurship monitor, "by the time they reach their retirement years, half of all working men in the united states probably have a period of self-employment of one or more years; one in four may have engaged in self-employment for six or more years. participating in a new business creation is a common activity among u.s. workers over the course of their careers". in recent years, entrepreneurship has been claimed as a major driver of economic growth in both the united states and western europe.