3 percent of the global population

• 3 percent of the global population—more than 200 million people—live outside their country of birth
• Uncounted millions more have moved, or been moved, within their home borders.
• A great deal of this movement is forced, either by economic pressures or, increasingly, by damage to the environment or human conflict—both of which are exacerbated by rapid population growth.

http://ngm.nationalgeographic.com/earthpulse/crowding-planet-text