"The makeup of the global workforce is undergoing a seismic shift: In four years Millennials—the people born between 1977 and 1997—will account for nearly half the employees in the world. In some companies, they already constitute a majority."
Quote above from "Mentoring Millennials" in Harvard Business Review.
Read this fascinating article to learn more about Baby Boomers, Gen Xers, and Millennials. The article has a great chart "What Millennials Want."