A woman walks through flood water during heavy downpour at a street in Genoa, Italy, 10 October 2014. At least one person died due to flooding after heavy rains caused the Bisagno river, which runs through Genoa city to overflow. Part of the city was in black-out with flooded streets and parked cars dragged away by the water's force. (Photo by Luca Zennaro/EPA)

Riot police arrest an anti-government protester in Ouagadougou, capital of Burkina Faso, October 30, 2014. Thousands of protesters marched on Burkina Faso's presidential palace after burning the parliament building and ransacking state television offices on Thursday, forcing President Blaise Compaore to scrap a plan to extend his 27-year rule. Emergency services said at least three protesters were shot dead and several others wounded by security forces when the crowd tried to storm the home of Compaore's brother. Security forces also fired live rounds and tear gas at protesters near the presidency in the Ouaga 2000 neighborhood. (Photo by Joe Penney/Reuters)

Indian commuters travel in a local train in Kolkata, India, Tuesday, February 26, 2013. Indian Railway Minister Pawan Kumar Bansal is presenting the country's rail budget for next fiscal year in the parliament Tuesday, Feb. 26, 2013. Indian railway network is one of the world's largest, with some 14 million passengers daily and some 64,000 kilometers (40,000 miles) of railway track cut through some of the most densely populated cities. (Photo by Bikas Das/AP Photo)

A prototype battery-powered plane, called Greased Lightning or GL-10 is pictured flying at NASA's Langley Research Center in this undated handout photo obtained by Reuters May 1, 2015. The plane, which has 10 engines and can take off like a helicopter and fly efficiently like an aircraft, is currently in the design and testing phase. (Photo by Reuters/NASA)

A model wears a floral head dress as she promotes a chain of garden centres at the Royal Horticultural Soceity's Chelsea Flower Show in London, Britain, May 18, 2015. (Photo by Toby Melville/Reuters)

A commuter gestures to Boris Johnson as he rides across Vauxhall Bridge in London, England on November 19, 2015. The London mayor was opening a cycle superhighway. (Photo by John Stillwell/PA Wire)

A donkey savors warming temperatures after a long winter at the zoo in Warsaw, Poland, on Wednesday, April 8, 2015. (Photo by Czarek Sokolowski/AP Photo)

Mercedes Formula One driver Lewis Hamilton of Britain sprays champagne at a grid girl as he celebrates his victory on the podium after the Chinese F1 Grand Prix at the Shanghai International Circuit, April 12, 2015. (Photo by Carlos Barria/Reuters)