In the early 90s, Maine students read at a higher level than kids in the nation as a whole. But in recent years, Maine's reading scores on a key national achievement test have been flat. Now, elementary school students here do no better than their peers in other states. One in five adults, meantime, is stuck at the lowest level of literacy, according to the group Literacy Volunteers of Maine. In Lewiston today, education officials unveiled a comprehensive strategy designed to arrest these trends and improve reading in Maine from birth through adulthood.