The Massachusetts economy may be booming, but have you ever wondered where local companies, large and small, are finding their new employees? The answer will surprise you. The Changing Workforce, a joint research project of MassINC and Citizens Bank, discovered that since the mid-1980s foreign immigrants, not native-born workers, account for an astounding 82 percent of the net growth in the state's labor force. Even more surprising, the Northeastern University researchers authoring this study, found that the Massachusetts population would have actually shrunk in every decade since the 1970s were it not for foreign immigration.