A simulated casualty is evacuated during an emergency services exercise at the disused Aldwych underground station on February 22, 2012 in London, England. Operation Forward Defensive aims to test the response to a terrorist incident on the London Underground network during the 2012 Olympic Games. (Photo by Peter Macdiarmid/Getty Images)

An injured supporter of Ivory Coast's Laurent Gbagbo reacts outside the premises of Hotel Golf, where Gbagbo is currently being held after his arrest, in Abidjan April 11, 2011. The trial of Laurent Gbagbo on charges of crimes against humanity during post-election violence, in which around 3,000 people were killed, will begin on January 28, 2016 at the International Criminal Court. (Photo by Reuters/Stringer)

Australian ballet dancers rehearse their moves on Whitehaven Beach on June 11, 2010 on Hamilton Island, Australia. (Photo by James Morgan/Hamilton Island via Getty Images)

Dancers of the English National Ballet perform The Nutcracker at the Coliseum on December 14, 2011 in London, England. (Photo by Ian Gavan/Getty Images)

A dancer from the Trisha Brown Dance Company performs during “Roof Piece” above the High Line park June 9, 2011 in New York City. Roof Piece (1971) consists of nine dancers performing improvised movement signals to each other in a chain on various rooftops overlooking the city. This presentation marked the first full performance of the piece since 1973. (Photo by Mario Tama/Getty Images)

Lady Gaga performs on ABC's “Good Morning America” at Rumsey Playfield, Central Park on May 27, 2011 in New York, United States. (Photo by Andrew H. Walker/Getty Images)

Members of China Disabled Peoples Performing Art Troupe perform “Thousand-arm Goddess of Mercy” during a show on March 12, 2005 in Guangzhou of Guangdong Province, China. China Disabled Peoples Performing Art Troupe was established in 1987. It is an amateur mass art troupe composed of visually impaired, audibly impaired and physically and mentally challenged people. In the past nearly two decades, the troupe has visited more than 30 countries and regions, winning the hearts of audiences all over the world by their solid background of Chinese Culture and their colourful national charm. (Photo by China Photos/Getty Images)

A group of people wearing full solid-coloured bodysuits walk along a promenade as they take part in a street art performance in Bat Yam, near Tel Aviv, Israel August 29, 2015. Some 40 people participated on Saturday in the performance, initiated by a group of artists called Prizma Ensemble, as part of the city's annual international street art and street theatre festival. The group says the performance deals with concepts of identity and movement in public spaces. (Photo by Amir Cohen/Reuters)