The U.S. opioid crisis that’s sweeping through America’s heartland has hit farmers harder than the wider rural population. Almost three-quarters of U.S. farmers and farm workers say they have been directly affected by opioid dependence, either from taking an illegal dose or dealing with a habit themselves, or by knowing someone who has used. That compares with about 45 percent for the rural population as a whole, according to a poll commissioned by the American Farm Bureau Federation and the National Farmers Union, the two biggest U.S. farmer groups.