Anti-government protesters celebrate inside Tahrir Square after the announcement of Egyptian President Hosni Mubarak's resignation in Cairo, Egypt, February 11, 2011. Picture taken February 11, 2011. REUTERS/Amr Abdallah Dalsh

A member of a Red Cross team walks in front of a boat sitting atop a building more than two weeks after the area was devastated by a magnitude 9.0 earthquake and tsunami in Otsuchi, northern Japan, March 28, 2011. Picture taken March 28, 2011. REUTERS/Damir Sagolj

Militant Islamist fighters take part in a military parade along the streets of northern Raqqa province, Syria, June 30, 2014. Picture taken June 30, 2014. REUTERS/Stringer

Lesleigh Coyer, 25, of Saginaw, Michigan, lies down in front of the grave of her brother, Ryan Coyer, who served with the U.S. Army in both Iraq and Afghanistan, at Arlington National Cemetery in Virginia, U.S., March 11, 2013. Picture taken March 11, 2013. Coyer died of complications from an injury sustained in Afghanistan. REUTERS/Kevin Lamarque

Residents sift through the ruins of their houses after a fire in Makati city, Metro Manila, Philippines, April 19, 2011. Picture taken April 19, 2011. REUTERS/Erik de Castro

Uttara Saud, 14, sits inside a Chaupadi shed in the hills of Legudsen village in Achham District in western Nepal, February 16, 2014. Chaupadi is a tradition observed in parts of Nepal, which cuts women off from the rest of society when they are menstruating. Women who practice traditional chaupadi have to sleep in sheds or outbuildings while they are on their period. Chaupadi was banned by Nepal's Supreme Court in 2005, but it is still common in the country's far and mid-western regions. Picture taken February 16, 2014. REUTERS/Navesh Chitrakar

Leaves cover the face of 11-month-old Rohingya refugee Abdul Aziz, after his body was brought back to the family shelter, at the Balukhali refugee camp near Cox's Bazar, Bangladesh, a few hours after he died on December 4, 2017. Aziz, whose family fled Myanmar some two months ago, died at a local clinic after suffering from high fever and severe cough for ten days, his mother said. Picture taken December 4, 2017. REUTERS/Damir Sagolj

Britain's Prince William and his wife Catherine, Duchess of Cambridge, kiss on the balcony at Buckingham Palace, watched by bridemaids Grace van Cutsem (L), Margarita Armstrong-Jones and pageboy Tom Pettifer, after their wedding in Westminster Abbey in London, Britain, April 29, 2011. Picture taken April 29, 2011. REUTERS/Dylan Martinez

Syrian rebels dodge debris after the wall which they were taking cover behind is hit by a shell fired from a government controlled checkpoint during fighting in the Ain Tarma neighbourhood of Damascus, Syria, January 30, 2013. Picture taken January 30, 2013. REUTERS/Goran Tomasevic

A demonstrator looks at a riot policeman during a protest marking the country's 1973 military coup in Santiago, Chile, September 11, 2016. Picture taken September 11, 2016. REUTERS/Carlos Vera

Marooned flood victims looking to escape, grab the side bars of a hovering Army helicopter which arrived to distribute food supplies in the Muzaffargarh district, Punjab province, Pakistan, August 7, 2010. Picture taken August 7, 2010. REUTERS/Adrees Latif

A man cries as he carries his daughter while walking from an Islamic State controlled part of Mosul towards Iraqi special forces soldiers during a battle in Mosul, Iraq, March 4, 2017. Picture taken March 4, 2017. REUTERS/Goran Tomasevic

A wave approaches Miyako City from the Heigawa estuary in Iwate Prefecture after a magnitude 8.9 earthquake struck the area in Miyako, Japan, March 11, 2011. Picture taken March 11, 2011. REUTERS/Mainichi Shimbun

A woman cries while sitting on a road after an earthquake and tusnami destroyed the city of Natori, Miyagi Prefecture in northern Japan, March 13, 2011. Picture taken March 13, 2011. REUTERS/Asahi Shimbun

Women carrying children run for safety as armed police hunt gunmen who went on a shooting spree in Westgate shopping centre in Nairobi, Kenya, September 21, 2013. Picture taken September 21, 2013. REUTERS/Goran Tomasevic

The Northern Lights are seen above the ash plume of a volcano in Eyjafjallajokull, Iceland, April 22, 2010. Picture taken April 22, 2010. REUTERS/Lucas Jackson

A garden with a swimming pool is inundated by the waters of the Elbe river during floods near Magdeburg in the federal state of Saxony Anhalt, Germany June 10, 2013. Picture taken June 10, 2013. REUTERS/Thomas Peter

Pro-European integration protesters take cover from water sprayed from a fire engine at the site of clashes with riot police in Kiev, Ukraine, January 23, 2014. Picture taken January 23, 2014. REUTERS/Vasily Fedosenko

A boy holds his mother's leg as he cries in front of their damaged house after a 6.6 magnitude earthquake at Longmen village, Lushan county in Ya'an, Sichuan province, China, April 21, 2013. Picture taken April 21, 2013. REUTERS/Jason Lee

A man is doused with milk and sprayed with mist after being hit by an eye irritant from security forces in Ferguson, Missouri, U.S., August 20, 2014. Picture taken August 20, 2014. REUTERS/Adrees Latif

Pakistani teenage activist Malala Yousafzai, who was shot in the head by the Taliban for campaigning for girls' education, signs a copy of her book before an event launching her memoir, "I Am Malala", at the Southbank Centre in central London, Britain, October 20, 2013. Picture taken October 20, 2013. REUTERS/Olivia Harris

Usain Bolt (JAM) of Jamaica looks at Andre De Grasse (CAN) of Canada as they compete in the 2016 Rio Olympics, Men's 100m Semifinals at the Olympic Stadium in Rio de Janeiro, Brazil, August 14, 2016. Picture taken August 14, 2016. REUTERS/Kai Pfaffenbach

A plane flies through the "Tribute in Lights" marking the 10th anniversary of the 9/11 attacks in lower Manhattan, New York, U.S., September 10, 2011. Picture taken September 10, 2011. REUTERS/Eric Thayer

An injured child receives medical treatment after a 7.0 magnitude earthquake in Port-au-Prince, Haiti, January 13, 2010. Picture taken January 13, 2010. REUTERS/Eduardo Munoz

Pope Benedict XVI enters a building during his visit to Lambeth Palace in London, Britain, September 17, 2010. Picture taken September 17, 2010. REUTERS/Stefan Wermuth

People watch from a nearby building as a fire burns in a slum in Mumbai, India, March 4, 2011. Picture taken March 4, 2011. REUTERS/Vivek Prakash

A Free Syrian Army fighter fires his sniper rifle from a house in Aleppo, Syria, August 14, 2012. Picture taken August 14, 2012. REUTERS/Goran Tomasevic

Rebels hold a young man at gunpoint, who they accuse of being a loyalist to Libyan leader Muammar Gaddafi, between the towns of Brega and Ras Lanuf, Libya, March 3, 2011. Picture taken March 3, 2011. REUTERS/Goran Tomasevic

A dinghy overcrowded with Syrian refugees drifts in the Aegean sea between Turkey and Greece after its motor broke down off the Greek island of Kos, August 11, 2015. Picture taken August 11, 2015. REUTERS/Yannis Behrakis

Venezuela's President and presidential candidate Hugo Chavez speaks in the rain during his closing campaign rally in Caracas, Venezuela, October 4, 2012. Picture taken October 4, 2012. REUTERS/Jorge Silva