Fighters of the Popular Resistance Committees stand during a graduation ceremony of the affiliate special forces of the Popular Resistance, in Yemen's southwestern city of Taiz October 8, 2015. (Photo by Reuters/Stringer)

People in an illuminated cycle rickshaw look at a light installation at the Old Royal Library during the opening day of the "Festival of Light" show in Berlin, Germany, October 9, 2015. (Photo by Hannibal Hanschke/Reuters)

A man wearing a mask and dressed in a clown costume rides an electric tricycle while carrying a container in the shape of a rubber duck amid heavy smog in Beijing, China, December 29, 2015. (Photo by Jason Lee/Reuters)

People line up to pay inside a Makro supermarket in Caracas, January 9, 2015. Venezuela's socialist government decreed an “economic emergency” on Friday that will expand its powers and published the first data in a year that shows the depth of a recession fueled by low oil prices and a sputtering state-led model. (Photo by Jorge Silva/Reuters)

A reveller walks through the streets in the early hours during traditional May Day celebrations in Oxford, Britain, May 1, 2015. (Photo by Dylan Martinez/Reuters)

Labourers work at the installation site of Liquefied Petroleum Gas (LPG) pipeline on May Day or Labour Day in Chandigarh, India, May 1, 2015. (Photo by Ajay Verma/Reuters)

Women look at a collapsed building caused by earthquakes, in Bhaktapur, Nepal, May 18, 2015. Nepal is facing billions in reconstruction costs with almost 745,600 buildings and homes damaged or destroyed, including at least 87,700 in the capital, according to Nepal's emergency authority. (Photo by Ahmad Masood/Reuters)

Activists from People for the Ethical Treatment of Animals (PETA) promoting a vegan diet are pictured as people drive past in Los Angeles, California May 21, 2015. (Photo by Mario Anzuoni/Reuters)