An Airbus A380 aircraft prepares to land at Mumbai airport in this May 8, 2007 file photo. Sentiment at some of Asia's biggest firms deteriorated again in the fourth quarter, falling to a four-year low under the weight of concerns about slowing growth in China, the region's biggest economy, a Thomson Reuters/INSEAD survey showed. (Photo by Arko Datta/Reuters)

In this Saturday, March 21, 2015 photo, a porter rests carrying supplies for the upcoming climbing season, near the Everest Base camp, Nepal. Nepal has cleared more than 300 mountaineers to climb Mount Everest after they had to abandon last year's efforts when an ice avalanche killed 16 guides in the mountain's deadliest disaster, an official said on March 20. The three-month climbing season for Everest, the world's tallest mountain, begins in March. (Photo by Tashi Sherpa/AP Photo)

Senator Barack Obama (D-IL) (R) stands in front of Senator Hillary Clinton (D-NY) as they arrive for U.S. President George W. Bush's annual State of the Union speech to a joint session of Congress at the U.S. Capitol in Washington in this January 23, 2007 file photo. Hillary Clinton announced her second run for the presidency on April 12, 2015 starting her campaign as the Democrats' best hope of fending off a crowded field of lesser-known Republican rivals and retaining the White House. (Photo by Larry Downing/Reuters)

In this July 30, 2014 photo, neighbors help gravely injured Mohammed al-Selek, 39, wounded by an Israeli mortar strike as he lays next to the body of Palestinian journalist Rami Reyan who was killed, in the Shijaiyah neighborhood of the northern Gaza Strip. Al-Selek's life changed forever last July 30, when the shells slammed into his home killing all his three children, his father and six other relatives. A year later, al-Selek, who lost his leg during the airstrike, still struggles to recover and come to terms with his family's loss in the 50-day Israel-Hamas war. (Photo by Adel Hana/AP Photo)

A girl uses her mobile phone during the evening at the National Park in Khartoum, Sudan, April 24, 2015. (Photo by Mohamed Nureldin Abdallah/Reuters)

A reveler jumps over a bonfire during the night of San Juan in Alcobendas near Madrid, Spain, Wednesday, June 24, 2015. The San Juan night coincides with the Summer solstice and it's the welcome to Summer. This celebration takes place during the shortest night of the year in almost all cities and towns of Spain. (Photo by Andres Kudacki/AP Photo)

Kazakh troops march during a parade of the armed forces to mark the Defender of the Fatherland Day in Astana, May 7, 2014. (Photo by Mukhtar Kholdorbekov/Reuters)

Hucul horses play in the wild meadows and forests near Odrzychowa in southeastern Poland on October 18, 2014. Huculs, a primitive breed of horse, escaped total extinction due to the efforts of scientists and Polish farmers. (Photo by Janek Skarzynski/AFP Photo)