By NICHOLAS KRISTOF As the world follows the drip-drip of sensational revelations about Jeffrey Epstein, here’s a number to ponder: Last year the National Center for Missing & Exploited Children received more than 113,000 reports of child sex trafficking. Yiota Souras, the center’s chief legal officer, says that while no one knows the actual number of children trafficked annually in the United States alone, “the real number is absolutely higher” than that. Most of the victims reported to her...