More than 13,000 unaccompanied illegal minors have been deported by Mexico after being caught at its southern border while the United States has not deported one undocumented child this year, government sources told BuzzFeed.

The figures represent 93 percent of the 14,000 undocumented children who entered Mexico illegally from Central American countries. Mexico also booted more than 64,000 of 69,000 adults who were seized this year at its southern border.

The United States, on the other hand, has detained 60,000 Central American minors this year, mainly from El Salvador, Guatemala, and Honduras, without deporting any of them.

The children, which are expected to number 90,000 by year’s end, must first be processed through an immigration system that allows them to apply for asylum, possibly due to the dangers they face back in their own country, a Department of Homeland Security spokesman said.

“Due to the current backlog in the courts, a [minor] encountered this year wouldn’t have yet had their day in immigration court,” the spokesman told BuzzFeed. “So all the [minors] encountered this year still have their cases pending.”

Mexican government sources said the majority of unaccompanied minors are age 12-17, and most are boys. They are sent home to their Central American countries by plane, while those who are accompanied by adult family members are given bus tickets back home.

Mexico is trying to crack down on the flow of minor migrants into Mexico by tightening  its border with Belize and Guatemala through increased checkpoints.

A Mexican official told BuzzFeed, meanwhile, that the number of Mexicans leaving the country for the United States is equal to the number of Mexicans who are returning home.