Soldiers from 12 Mechanized Brigade perform a simulated casualty evacuation at the Ministry of Defence training area at Copehill Down on Salisbury Plain on March 9, 2012 in Wiltshire, England. The Defence Secretary Philip Hammond visited the military facility to meet soldiers from the Brigade who are shortly to deploy to Afghanistan for Operation Herrick 16, and troops from the 3rd Battalion, the Yorkshire regiment which lost five of the six men who died this week in the deadliest single attack in Afghanistan since 2001. (Photo by Matt Cardy/Getty Images)

Brazilian natives of the Pareci tribe play head football with a hand-made ball for a demonstration, during the first day of the International Games of Indigenous Peoples, in Cuiaba, state of Mato Grosso, on November 10, 2013. 1500 natives from 49 Brazilian ethnic groups and from another 17 countries are gathering in Cuiaba until November 16 to compete in some 30 athletic disciplines, many of their own. (Photo by Christophe Simon/AFP Photo)

Abigail Crouse lifts her Thor hammer high after running through Sleeping Beauty's Castle during the Avengers Super Heroes Half Marathon in and around the Disney Parks in Anaheim, California November 16, 2014. Walt Disney Co has moved aggressively into the race business, attracting tens of thousands of runners every year to its marathons, half-marathons and family-friendly races. (Photo by Eugene Garcia/Reuters)

Myanmar revellers take part in celebrations on the fifth and last day marking Thingyan, a water festival which brings in the country's new year, in Yangon on April 16, 2016. The Buddhist festival of water pouring symbolizes spiritual cleansing and begin the new year free from worldly impurities with celebrants devoting the four days of Thingyan in merry making of water dousing until the eve of new year. (Photo by Romeo Gacad/AFP Photo)

A porter stands at the bottom of the Illimani mountain, on the outskirts of La Paz, Bolivia, April 16, 2016. For years, Lydia Huayllas, 48, has worked as a cook at base camps and mountain-climbing refuges on the steep, glacial slopes of Huayna Potosi, a 19,974-foot (6,088-meter) Andean peak outside of La Paz, Bolivia. But two years ago, she and 10 other Aymara indigenous women, ages 42 to 50, who also worked as porters and cooks for mountaineers, put on crampons – spikes fixed to a boot for climbing – under their wide traditional skirts and started to do their own climbing. (Photo by David Mercado/Reuters)

Juanita Robinson (L) from Ohio and Trenaya Blackburn pose as Quan White from Michigan takes their picture as they vacation on South Beach on May 16, 2016 in Miami Beach, Florida. The Florida government announced it broke a tourism record in the first quarter of this year, attracting 29.8 million tourists, an increase of 4.8 percent over the same time frame in 2015. (Photo by Joe Raedle/AFP Photo)

A Palestinian boy takes part in a military-style summer camp being held by the Islamic Jihad movement during the youngsters' summer school vacation in Khan Younes town, in the southern Gaza Strip, 13 July 2016. Thousands of youngsters between the age of six and 16 can participate in the summer camp where they receive military as well as religious training. (Photo by Hatem Omar/EPA)

In this Tuesday, May 3, 2016 photo, Madeley Vasquez, 16, breast feeds her one-year-old son Joangel as she waits in line outside a supermarket to buy food in Caracas, Venezuela. Vasquez once ran down the block to avoid getting caught up in a knife fight that broke out when a woman was accused of cutting the line. (Photo by Ariana Cubillos/AP Photo)