Summer Olympic Games demand for tickets to all levels of each event, there was controversy when seats set aside for sponsors and National Delegations went unused in the early days. A system of reallocation was put in place so the empty seats were filled throughout the Games. Rio de Janeiro, Brazil hosted the 2016 Summer Olympics, becoming the third city in the Southern Hemisphere to host the Olympic Games after Melbourne, Australia, in 1956 and Sydney, Australia, in 2000, and the first South American city to host the Olympics. The preparation for these Games was overshadowed by controversies, including the instability of Brazil's
Summer Olympic Games federal government; the country's economic crisis; health and safety concerns surrounding the Zika virus and significant pollution in the Guanabara Bay; and a state-sponsored doping scandal involving Russia, which affected the participation of its athletes in the Games. Tokyo, Japan will host the 2020 Summer Olympics, making it the first Asian city to host the Olympic Games twice. Forty-two sports, spanning 55 disciplines, have been part of the Olympic program at one point or another. Twenty-eight sports have comprised the schedule for three of the recent games, 2000, 2004, and 2008 Summer Olympics. Due to the removal of baseball and