2017-22 Comparisons
A more detailed analysis is provided in Atan, Çavdaroğlu and Özcan Yavuz (2023): Preprint, "A comparison of management policies for referee appointments in European men's football", https://doi.org/10.21203/rs.3.rs-2700365/v1.
a: France had a few referees from Switzerland (2017-18, 2019-20) and Portugal (2021-22) each officiating one game.b: Foreign referees not included. c: During the Covid-19 pandemic, most games in the second half of the season were cancelled.