A woman performs during a march to commemorate International Day for the Elimination of Violence Against Women, in Bogota, November 25, 2015. (Photo by John Vizcaino/Reuters)

A pig's head is seen in a basin after it was slaughtered it in the village of Azerany, Belarus, December 12, 2015. (Photo by Vasily Fedosenko/Reuters)

Damaged buildings are pictured at night in Aleppo, Syria December 11, 2015. (Photo by Ammar Abdullah/Reuters)

Passengers travel on the London train and underground system during the Christmas party season, December 18, 2015. (Photo by Paul Hackett/Reuters)

Participants prepare backstage during Belarus bodybuilding and fitness championship in Minsk April 25, 2015. (Photo by Vasily Fedosenko/Reuters)

A six-year-old acrobat performs on the opening of a tourist festival in Bozhou, Anhui province, China May 3, 2015. (Photo by Reuters/China Daily)

People take photos with the skyline of the central business district in Singapore on September 10, 2015. (Photo by Edgar Su/Reuters)

Ukrainian Air Force officers attend a graduation ceremony at the National University of Defence of Ukraine in Kiev, April 24, 2015. (Photo by Gleb Garanich/Reuters)