Air passenger traffic dropped by 60% in March 2020, compared to March 2019, according to Eurostat, the EU statistics bureau.
In terms of total passenger numbers, Germany reported 10.7m fewer passengers, followed by Denmark (1.7m), Finland (1.1m) and the Czech Republic (824,000).
Luxembourg lost 192,000 air travellers.
Findel airport was closed between late March and late May. Luxair, Lufthansa and Ryanair have all reintroduced Luxembourg flights.
Eurostat released the figures, which only cover 13 EU member states, on 16 June.