Russian Mi-28N from the Berkuty (Golden Eagles) helicopter display team fly in formation during the “Aviadarts” military aviation competition at the Dubrovichi range near Ryazan, Russia, August 2, 2015. The aircraft started dipping down due to back propeller failure and crashed, killing one of two pilots, according to a Reuters photographer and official representatives of the competition. The aviation contest is part of the International Army Games, which are held in Russia from the 1st till the 15th of August with participants from 17 countries, according to organizers. (Photo by Maxim Shemetov/Reuters)

Dressed up as Punxsutawney Phil, Marty Nagy, of Hallandale Beach, Fla., gives thumbs up to passers by before the start of the 12th annual Groundhog Day on Hollywood Beach, Tuesday, February 2, 2016, in Hollywood, Fla. The event, which featured breakfast and an ocean plunge, benefited the Hollywood Beach Lifeguard Competition Team. (Photo by Wilfredo Lee/AP Photo)

Labourers pour molten iron into a container at a foundry in Xiangfan, Hubei province in this July 2, 2010 file photo. Iron ore is enjoying its biggest rally in years, outpacing copper and oil so far in 2016, but still weak forward prices show it may be tough to stretch the bullish outlook. Improving steel prices in top market China are helping fuel iron ore's climb as producers gear up for a seasonal uptick in demand. Yet there is no shortage of doubters who see gains in the bulk commodity as fleeting given a large glut and challenges for China's economy. (Photo by Reuters/Stringer)

Blind and visually impaired Palestinian students walk down the stairs at a school, where they are taught English through song and music, at a school in the West Bank city of Hebron March 2, 2016. Palestinian students at a school for the blind in the West Bank are learning English through song, a welcome departure from using braille and memorising grammar rules. While students are delighted with the change, some parents in the religiously conservative town of Hebron are concerned that using music in the classroom jars with Islamic tradition. (Photo by Ammar Awad/Reuters)

In this April 2, 2016 photo, dusty sculptures made of cast-off baby dolls sit in an open-air museum and art workshop off a trash-strewn street cutting through some of the poorest neighborhoods in Port-au-Prince, Haiti. They were created by Haitian artists called Atis Rezistans who have become celebrated in the international art world by creating sculptures out of scrapped car parts, old wood, discarded toys and even human skulls found scattered outside crumbling mausoleums. (Photo by David McFadden/AP Photo)

This April 9, 2016 photo provided by Bertrand Piccard via Global Newsroom shows Piccard taking a selfie on board Solar Impulse 2 during a test flight over the Pacific Ocean. The solar-powered airplane on an around-the-world journey had traveled 80 percent of the way from Hawaii to California by Saturday, April 23. The aircraft's destination on this leg of the journey is Mountain View, Calif., at the southern end of San Francisco Bay. (Photo by Bertrand Piccard/Global Newsroom via AP Photo)

A surfer runs down the beach past hundreds of Barbie dolls comprising the sculpture 'Wave 2' by West Australian artist Annette Thas on Tamarama Beach during the 19th annual Sculptures by the Sea exhibition in Sydney, October 23, 2015. Sydney's coastal walk between Bondi and Tamarama has been transformed into a temporary sculpture park featuring over 100 sculptures from Australian and international artists, billed as the largest free sculpture exhibition in the world. (Photo by Jason Reed/Reuters)

A driverless vehicle runs at Vanke's Building Research Centre testing area in Dongguan, south China's Guangdong province November 2, 2015. The country's largest property developer, China Vanke, is investing in its own robots to do certain jobs in the face of a labor shortage in the world's most populated country. This driverless car is among the robots that Vanke is aiming to bring in. (Photo by Tyrone Siu/Reuters)