Michigan, like many other states, says it has a shortage of skilled workers, a gap that risks hurting its economy. Only 51.6 percent of working-age adults over 25 have a degree or other training beyond high school, state data shows, the lowest of any Midwestern state. The number of men in particular who are going to college has been falling steadily, despite evidence that people with postsecondary credentials tend to earn more than their peers with only a high school diploma and are more likely to be employed.