An Afghan policeman carries a wounded man at the site of a suicide attack in Kabul March 25, 2015. Six people were killed and more than 30 injured in the suicide bombing in the Afghan capital on Wednesday that struck close to the presidential palace in the heart of the city, the Interior Ministry said. The suicide bomber had been travelling in a vehicle packed with explosives and it was not immediately clear what the target of the attack had been. (Photo by Omar Sobhani/Reuters)

In this March 15, 2012 file photo, a Chinese woman poses for photos near a sculpture depicting a Chinese yuan note at an art district in Beijing, China. China devalued its tightly controlled currency on Tuesday, August 11,2015, following a slump in trade, triggering the yuan's biggest one-day decline in a decade. The central bank said the yuan's 1.3 percent fall was due to a change aimed at making its exchange rate controls more market-oriented. But any change raises the risk of tensions with China's trading partners. (Photo by Ng Han Guan/AP Photo)

A police officer gives instructions to migrants rushing to board a train that would take them towards Serbia, at the railway station in the southern Macedonian town of Gevgelija, Wednesday, August 20, 2015. Macedonian police stepped up the security at the border with Greece apparently trying to stem recent surge of migrants who are coming from Greece. (Photo by Darko Vojinovic/AP Photo)

In this September 16, 1983 file photo, actor and bodybuilder Arnold Schwarzenegger shows off his new U.S. citizenship papers as Maria Shriver, daughter of Sargent and Eunice Shriver, looks on at the Shrine Auditorium in Hollywood, Calif. (Photo by Wally Fong/AP Photo)

An ethnic Kayaw couple Mu Htoo and her husband Htaw Eili rest at their home at Htaykho village in the Kayah state, Myanmar September 12, 2015. With about 30,000 members, the Kayaw are one of the smallest ethnic minorities among Myanmar's 135 groups. Their village has for decades been off-limits, as armed rebels fought the military before a recent ceasefire stopped the bloody conflict here. The rebels in the area have put down their guns and taken to the hills to grow rice and corn, but slash-and-burn cultivation methods mean they struggle to find new places to farm. (Photo by Soe Zeya Tun/Reuters)

The coendou porcupine couple 'Joppi' (L) and 'Fletcher' nibble at a vegetables in their enclosure at the zoo in Frankfurt am Main, Germany, 03 December 2015. Coendou porcupines are nocturnal rodents related to porcupines and guinea pigs and native to the rain forests of Central and South America as well as Trinidad. (Photo by Arne Dedert/EPA)

A basket of olives sits in an olive tree field in La Rinconada, near the Andalusian capital of Seville September 24, 2012. (Photo by Marcelo del Pozo/Reuters)

A pro-democracy protester wearing a Guy Fawkes mask holds a yellow umbrella and a banner in the part of Hong Kong's financial central district protesters are occupying November 2, 2014. The former British colony of Hong Kong, which returned to Chinese rule in 1997, has witnessed a month of protests calling on the Beijing-backed government to keep its promise of introducing universal suffrage. The protests have for the most part been peaceful, with occasional clashes between the student-led protesters and Beijing supporters seeking to move them from the streets. (Photo by Damir Sagolj/Reuters)