The following data is coming from an article posted on nikkei.com – Nikon kept the #2 spot in interchangeable lens camera shipments for 2019, but in the mirrorless segment, Nikon is even behind Olympus (Olympus basically gave up on their camera business):
Shipments of interchangeable lens cameras in 2019:
Mirrorless camera shipments in 2019:
2019 camera market share: Canon 45.4%, Sony 20.2%, Nikon 18.6%, Fuji 4.7%, Panasonic 4.7%
Via Digicame-info