In what may give impetus to renewed attention to health-care reform legislation in the next Congress, a study by the nonpartisan Employee Benefit Research Institute (EBRI), Washington, D.C., indicates that the number of Americans who do not have health insurance continues grow. More than 43 million -- 18.3% of nonelderly Americans -- had no coverage in 1997, up from 41.4 million (or 17.7%) in 1996, says EBRI. The analysis focuses on Americans under age 65 because more than 96% of those over 65 are covered by federal Medicare insurance. Employment-based health plans remained the most common source of coverage in 1997, extending to nearly 152 million nonelderly Americans (64.2%), the study reveals. That percentage has been rising for years, climbing from 63.5% in 1996.