The number of people arrested for attempting to cross illegally into the United States from Mexico declined for a seventh consecutive month and now stands at one-quarter of what it was at its peak last May.

Data released Thursday by U.S. Customs and Border Protection shows 32,858 people who tried to illegally cross from Mexico into Arizona, California, New Mexico, and Texas were taken into custody by Border Patrol agents in December. That number is down from 132,887 last May, when border activity peaked due to a surge of Central American families.