Summer Olympic Games Australia (1956, 2000) and Brazil (2016). Africa has yet to host a Summer Olympics. Stockholm, Sweden, has hosted events at two Summer Olympic Games, having been sole host of the 1912 Games, and hosting the equestrian events at the 1956 Summer Olympics (which they are credited as jointly hosting with Melbourne, Australia). Amsterdam, Netherlands, has also hosted events at two Summer Olympic Games, having been sole host of the 1928 Games and previously hosting two of the sailing races at the 1920 Summer Olympics. At the 2008 Summer Olympics, Hong Kong provided the venues for the equestrian events, which took
Doping at the Olympic Games effort to detect banned substances and recent blood transfusions. While several athletes were barred from competition by their National Olympic Committees prior to the Games, six athletes failed drug tests while in competition in Beijing. What follows is a list of all the athletes that have tested positive for a banned substance either during or after an Olympic Games in which they competed. Any medals listed were revoked by the International Olympic Commission (IOC). In 1967 the IOC banned the use of performance-enhancing drugs, instituted a Medical Commission, and created a list of banned substances. Mandatory testing began at the