A woman crosses an open sewer as she makes her way to her house in a Christian slum in Islamabad December 4, 2014. (Photo by Zohra Bensemra/Reuters)

An Afghan refugee girl stands near her parents' makeshift shelter in a slum on the outskirts of Lahore January 12, 2015. (Photo by Zohra Bensemra/Reuters)

A garbage collector, with his horse and cart, prepares to unload rubbish at the municipal dump in Nezahualcoyotl, on the outskirts of Mexico City, February 18, 2015. Hundreds of horse or donkey-drawn carts will disappear from the streets of a municipality in the state of Mexico, located on the outskirts of Mexico City, and will be replaced by motorized vehicles, local authorities said. (Photo by Henry Romero/Reuters)

A model walks down the runway at the 13th China International Young Fashion Designers Contest during China Fashion Week on March 25, 2005 in Beijing, China. (Photo by China Photos/Getty Images)

Crashed cars in Finchley Road, north London. (Photo by Hulton Archive/Getty Images). May 1924

Shepherds lead their sheep through the centre of Madrid, Spain, Sunday, October 25, 2015. Shepherds have guided a flock of 2,000 sheep through Madrid streets in defense of ancient grazing, droving and migration rights increasingly threatened by urban sprawl and modern agricultural practices. Tourists and city-dwellers were surprised to see the capital's traffic cut to permit the ovine parade to bleat bells clanking its way past the city's most emblematic locations. (Photo by Daniel Ochoa de Olza/AP Photo)

A worker displays paper pandas created by French artist Paulo Grangeon in front of the Grand Palace in Bangkok, Thailand, Friday, March 4, 2016. The exhibit is part of the World Wide Fund's project where the 1600 paper pandas symbolize the last pandas still present in nature.(Photo by Sakchai Lalit/AP Photo)

A tow car for the children's “Grand Prix” races which take place in a parking lot in Livonia, Michigan a suburb of Detroit, circa 1955. (Photo by Three Lions/Getty Images)