The Chicago metro area saw its poverty rate drop to 12.4 percent in 2016 from 13.3 percent the year before, according to American Community Survey data released Thursday by the U.S. Census Bureau. Among the top 25 most populous metro areas — whose poverty rates ranged from 15.4 percent in Miami to 8.4 percent in the District of Columbia — 17 saw significant declines in the number of people living under the poverty line and the rest saw no statistically significant change.