From the Summary: "The number of unaccompanied alien children (UAC, unaccompanied children) apprehended at the Southwest border between U.S. ports of entry while attempting to enter the United States without authorization has increased substantially in recent years: from 16,067 in FY2011 to 24,481 in FY2012 to 38,759 in FY2013. In FY2014, the Department of Homeland Security (DHS), Customs and Border Protection (CBP) apprehended 68,541 UAC, a record at that time. Since FY2014, UAC apprehensions have fluctuated considerably, declining to 39,970 in FY2015, increasing to 59,692 in FY2016, declining to 41,435 in FY2017, and increasing to 50,036 in FY2018. In the first 11 months of FY2019, they reached 72,873, a level that now exceeds the FY2014 peak."
CRS Report for Congress, R43599
Congressional Research Service: https://crsreports.congress.gov/