In the 1980s, DB plans were still fairly common. According to the BLS, in 1981, more than 80% of full-time workers in large establishments were covered in a DB plan. Even in the early 1990s, about 35% of all workers in private sector establishments of all sizes were covered by a DB plan. As of 2011, the figure dropped to 18%. The one area in which DB coverage is still substantial is for state and local government employees (78% as of 2011), but even this is the subject of debate during state budget discussions.
One in four DB participants are in frozen plans (closed to future participants), with the percentage increasing as more people retire and no new participants can join the DB plan. While 10% of private industry employers offer DB plans, the figure is 48% for employers with 500+ employees. DB plans cover about two out of every three union members in private industry, but only about one in eight nonunion workers. The utility industry has the greatest DB coverage, with 81%; other industries trail far behind. The Mid-Atlantic and Midwest states have the greatest concentration of DB plans.
You can find the full article, The Last Private Industry Pension Plans: A Visual Essay, on the BLS website.