The report by the Commonwealth Fund, a healthcare advocacy group, said 71 percent of an estimated 26 million people who tried to buy insurance on the individual market in the previous three years had problems purchasing affordable insurance. About 35 percent said they were turned down or charged higher prices because of their medical history. A majority of Americans obtain health coverage through their employers. The study by the Commonwealth Fund, which conducts research and advocates for healthcare reform, also said millions of people who lost jobs in the last two years during the economic slump joined the ranks of the uninsured. About 52 million people living in the United States went without medical coverage for a period of time in 2010, the report said. That compares to 38 million people who went without healthcare coverage in 2001.