The share of poor Americans with health insurance rose substantially in 2014, according to the first full year of federal data since the Affordable Care Act extended coverage to millions of Americans last year. The percentage of insured Americans increased from 61 to 68 percent. The increase is largely in line with earlier findings by private polling companies such as Gallup, but was significant because of its source — the National Health Interview Survey, a long-running federal survey considered to be a gold standard by researchers.