Seven-in-ten American business owners consider rising health care costs to the primary threat to their current or future retirement, according to a new Millionaire Corner survey of 1,100 investors. “The cost of health insurance” has been ranked the top small-business problem for the last 25 years, according to “Small-Business Problems and Priorities,” an annual report issued by the National Federation of Independent Business. In the 2012 study, 52 percent of the more than 20,000 members who were randomly surveyed, said that the cost of health insurance was their top problem. In comparison, 38 percent said “Uncertainty over Economic Conditions” was the most critical problem they face according to a recent report at www.millionairecorner.com.