WASHINGTON - The percentage of physicians who provide free care to the poor has dropped over the past decade, signaling a growing problem for the uninsured, a survey suggests. About three-quarters of physicians provided charity care in the mid-1990s, compared with about two-thirds now, according to a study being released Thursday by the Center for Studying Health System Change. The numbers have declined across all major specialties. The highest rate of free care, 78.8 percent, comes from surgeons, perhaps because many of these doctors treat uninsured patients in emergency rooms. Just over 60 percent of pediatricians provided free care, the...