How many commercial jetliners have been fitted with ejection seats?

Ejection seats (or ejector seats) are considered an essential safety feature for modern military jets. Typically the seat is propelled out of the aircraft by an explosive charge or rocket motor, carrying the pilot with it.

They are not usually used for airliners, although there is an interesting exception. The only commercial jetliner ever fitted with ejection seats was the Soviet Tupolev Tu-144, colloquially known as "Concordski". However, the seats were present in the prototype only, and were only available for the crew and not the passengers. The Tu-144 that crashed at the Paris Air Show in 1973 was a production model, and did not have ejection seats.