A statistical study of the long-term evolution of coronal hole properties as observed by SDO S. G. Heinemann, V. Jerčić, M. Temmer, S. J. Hofmeister, M. Dumbović, S. Vennerstrom, G. Verbanac and A. M. Veronig A&A, 638 (2020) A68 Published online: 12 June 2020 DOI: 10.1051/0004-6361/202037613