Many Iowans buying federally subsidized health insurance could be in for a big price increase next year, The Des Moines Register reported. Coventry Health Care of Iowa, which is the main insurance carrier selling plans on the Iowa marketplace at healthcare.gov, is seeking to raise rates by at least 18 percent for the 2016 plan year. The proposed increases, which the insurer said were driven primarily by higher medical costs, would affect about 47,000 residents. The increases would not apply to people who obtain coverage from Coventry through their employer or government programs such as Medicare and Medicaid. Earlier this month, Wellmark Blue Cross and Blue Shield filed with the Iowa Insurance Division for a 28 percent increase on its non-grandfathered plans that are subject to Affordable Care Act rules. That rate increase would affect about 30,000 Wellmark policyholders who are under age 65.