A QUARTER OF ALL U.S. KIDS IN POVERTY: More than a quarter of all American children under age six were living below the poverty line in 1992 -- the highest rate in 25 years, a Columbia University study shows. This despite the fact that parents of 58 percent of them were working at least part-time, according to data from the study, which was based on U.S. Census Bureau statistics. The total number of young children who live below the official poverty line, according to the National Center for Children in Poverty, reached 6 million in 1992, up from 5 million from 1987. The poverty line is defined as an annual income of $14,335 for a family of four.