A man holds up for a picture a one hundred trillion Zimbabwean dollars note inside a shop in Harare, Zimbawe, June 12, 2015. Hyperinflation in Zimbabwe was a period of currency instability that began in the late 1990s shortly after the confiscation of private farms from landowners, towards the end of Zimbabwean involvement in the Second Congo War. During the height of inflation from 2008 to 2009, it was difficult to measure Zimbabwe's hyperinflation because the government of Zimbabwe stopped filing official inflation statistics. However, Zimbabwe's peak month of inflation is estimated at 79.6 billion percent in mid-November 2008. (Photo by Philimon Bulawayo/Reuters)

An injured boy who is undergoing surgery, after he was injured in what activists said was an airstrike by forces loyal to Syria's president Bashar al-Assad, rests inside a field hospital in the Douma neighborhood of Damascus, Syria December 5, 2015. Douma in Syria, an area controlled by rebels fighting to topple President Bashar al-Assad, has been shelled continuously for the past three years. The injured are taken to basements and shelters transformed into field hospitals run by medical staff who have stayed in the battered neighbourhood of Damascus. (Photo by Bassam Khabieh/Reuters)

Gohei Hayashi of Kyoto University is seen in side his movable eco and healing house, “Kujira (Whale) House” July 21, 2007 in Tokyo, Japan. The house is made from Japanese paper, bamboo and tatami mat. Hayashi has travelled 500 km from Japan's ancient city, Kyoto to Tokyo with his eco house to promote his house which can be placed both out inside and outside to provide a private space. The Kujira house is available at the price of 800,000 yen (roughly US$6600). (Photo by Koichi Kamoshida/Getty Images)

An Indonesian worker carries a giant candle at a traditional Chinese candle maker for the upcoming Lunar New Year in Bogor, Indonesia, 27 January 2015. The Chinese Lunar New Year, known here as Imlek, is only three weeks away. The whole city is getting decked out to celebrate the event on 19 February 2015. (Photo by Adi Weda/EPA)

The NASA Extreme Environment Mission Operations (NEEMO) 21 mission began on July 21 as an international crew of aquanauts splashed down to the undersea Aquarius Reef Base, located 62 feet below the surface of the Atlantic Ocean in the Florida Keys National Marine Sanctuary. The NEEMO 21 crew will perform research both inside and outside the habitat during a 16-day simulated space mission. During simulated spacewalks carried out underwater, they will evaluate tools and mission operation techniques that could be used in future space missions, including journeys to Mars. (Photo by Karl Shreeves/NASA)

A Yemeni soldier, pictured through a vehicle's windscreen, which was damaged by a bullet, gestures out of the window, in Marib, Yemen October 15, 2015. Marib is a city that is heavily armed even by the standards of Yemen, where the ready availability of weapons helped start civil war and is now preventing anyone coming out on top. Yemenis often say there are three guns for every person, a boast that has become an urgent concern in a country where the United Nations says the humanitarian situation is "critical". (Photo by Angus McDowall/Reuters)

A young girls holds a ballot during the Greek referendum in Athens on July 5, 2015. Greek voters headed to the polls today to vote in a historic, tightly fought referendum on whether to accept worsening austerity in exchange for more bailout funds, in a gamble that could see it crash out of the euro. (Photo by Aris Messinis/AFP Photo)

Girls cry as they get separated from their family at the border line dividing Macedonia and Greece August 21, 2015. At least 1,000 migrants and refugees pressed against Macedonian police lines on the Greek-Macedonian border on Friday and at least 10 people appeared to faint in the crush. People could be heard screaming and medical workers raced to treat those who passed out or were hurt. The crush ensued after police let several hundred through into Macedonia, having kept them out since Thursday under an emergency decree. (Photo by Ognen Teofilovski/Reuters)