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)

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

A mahout rides on an elephant in the city of Amritsar, India, 08 November 2015. Such elephants are often accompanied by their caretakers who ask for alms from people in the streets. (Photo by Raminder Pal Singh/EPA)

A model presents a creation by Maltese hairstylist Marielle Calleja of Prive at the Malta Fashion Awards 2015 at the Marsa Shipbuilding warehouse in Marsa, outside Valletta in Malta, May 16, 2015. (Photo by Darrin Zammit Lupi/Reuters)