A new international survey finds depression is the second-most disabling illness for workers. The World Federation of Mental Health survey found one-in-ten workers suffers from depression, anxiety, stress or burnout. That’s no surprise to Lance Clemsen, a counselor for the University of Iowa’s employee assistance program.Clemsen says up to 90 percent of visits to a doctor are for stress-related problems. He says some people become more productive with pressure, but the demands have continued to increase.The international survey concludes the despair suffered by workers costs businesses more than plant shutdowns or strikes. He says that’s not surprising to mental health experts.Clemsen says recent statistics show anti-depressants are the most commonly prescribed drugs in America. The World Federation for Mental Health released its survey yesterday to mark “World Mental Health Day” at a conference in Switzerland.