Militants loyal to Yemen's exiled government ride on the back of a pick-up truck in the country's central city of Taiz August 19, 2015. Militia forces loyal to Yemen's exiled government fought their way deep into the central city of Taiz this week, local officials said, largely pushing out Houthi militiamen from the country's third largest city. (Photo by Reuters/Stringer)

Displaced Sunni people, who fled the violence in the city of Ramadi, arrive at the outskirts of Baghdad, April 17, 2015. Iraqi security forces fought Islamic State militants at the gates of the western city of Ramadi on Friday, and local authorities warned it was in danger of falling unless reinforcements arrived soon. (Photo by Reuters/Stringer)

A car drives past burning trees as a wildfire rages in the northern city of Haifa, Israel November 24, 2016. Hundreds of Israelis fled their homes on the outskirts of the country's third city Haifa with others trapped inside as firefighters struggled to control raging bushfires, officials said. (Photo by Gil Eliyahu/Reuters)

People purchase the book “Steve Jobs” by Walter Isaacson on launch day at Shanghai's City of Books on October 24, 2011 in Shanghai, China. The book was launched in 30 book cities at the same time across the country. (Photo by ChinaFotoPress/Getty Images)

A man walks beside a “Wrinkles Of The City” creation near the Berlin cathedral in Berlin April 19, 2013. (Photo by Fabrizio Bensch/Reuters)

Dancers rehearse for the Rockettes 2015 Radio City Christmas Spectacular in New York October 15, 2015. (Photo by Lucas Jackson/Reuters)

A girl poses in her costume during a Halloween party at a mall in Quezon city, Metro Manila October 24, 2015. (Photo by Ezra Acayan/Reuters)

A man drinks at a "colored" water cooler in a streetcar terminal in Oklahoma City, July 1939. (Photo by Reuters/Library of Congress)