Passage: This is a list of nations, as represented by National Olympic Committees (NOCs), that have participated in the Summer Olympic Games between 1896 and 2016. As of the 2016 Games, all of the current 206 NOCs have participated in at least one edition of the Olympic Games, and athletes from Australia (including two Games featuring the Australasia team), France, Great Britain, Greece and Switzerland have competed in all twenty-eight Summer Olympic Games.

Question: how many summer Olympic games have been completed?
twenty-eight