Sources, in order of appearance:
U.S. Federal Aviation AdministrationU.S. Department of Transportation (Doesn’t include December, for which stats are not yet available)Heathrow AirportU.S. Transportation Security AdministrationProPublicaProPublicaU.S. Transportation Security AdministrationProPublica/TSAU.S. Federal Aviation AdministrationU.S. Federal Aviation AdministrationAerospaceweb.orgUSA TodayU.S. Department of Homeland SecurityU.S. Department of Homeland Security
