A 20 metre high spiral staircase in a tower used as an emergency exit, is seen inside a Federal Reserve bank (Bundesbank) bunker, prior to the bunker's official opening to the public in Cochem, Germany, March 18, 2016. West Germany's Central Bank (Deutsche Bundesbank) stored some 20 billion German marks of emergency notes in two underground bunkers, one in Frankfurt the other in Cochem, between 1964-1988 during the cold war. (Photo by Kai Pfaffenbach/Reuters)

People enjoy themselves as they dance to Dominican music at a refugee camp for Haitians returning from the Dominican Republic on the outskirts of Anse-a-Pitres, Haiti, September 6, 2015. Dominican officials last month began implementing a controversial immigration program targeting Haitian migrants and Dominican-born people of Haitian descent. The program centers on round-ups and deportations that have triggered concerns about a slow-growing border migration crisis in the poorest country in the Americas. So far about 1,500 people have been deported at a pace of 50 to 100 per day, according to relief officials with access to records supplied by the Dominican government. (Photo by Andres Martinez Casares/Reuters)

Passengers wait for a train to depart from the Hankou Railway Station in Wuhan, central China's Hubei province, Friday January 13, 2017. Officials expect that Chinese travelers will make almost 3 billion trips during the holiday travel rush that starts runs through Feb. 21. These trips include intercity flights, trains and local bus rides to villages for China's 1.4 billion people. (Photo by Chinatopix via AP Photo)

A young couple rest in a football field after a forest fire devastated Santa Olga, 240 kilometres south of Santiago, on January 26, 2017. Six people – among them four firefighters and two police – have now been killed battling vast forest fires in central Chile, officials said Wednesday. Multiple blazes have ravaged 238,000 hectares (588,000 acres) and are growing, the National Forestry Corporation said in a statement. (Photo by Pablo Vera Lisperguer/AFP Photo)

Family of passengers onboard AirAsia flight QZ8501 react at a waiting area in Juanda International Airport, Surabaya December 28, 2014. Indonesia's air force was searching for the AirAsia plane carrying 162 people that went missing on Sunday after the pilots asked to change course to avoid bad weather during a flight from the Indonesian city of Surabaya to Singapore. The Airbus 320-200 lost contact with Jakarta air traffic control at 6:17 a.m. (23:17 GMT), officials said. (Photo by Reuters/Beawiharta)

A large molded bust of Edward Snowden is pictured in Fort Greene Park at the Brooklyn borough of New York in this April 6, 2015 picture provided by ANIMALNewYork. A group of anonymous artists erected the 4-foot-tall bronze statue of Snowden, the former U.S. spy agency contractor famous for leaking classified information, in a New York City park overnight, officials said on Monday. (Photo by Aymann Ismail/Reuters/ANIMALNewYork)

Passengers embrace each other at the entrance to Istanbul's Ataturk airport, early Wednesday, June 29, 2016 following their evacuation after a blast. Suspected Islamic State group extremists have hit the international terminal of Istanbul's Ataturk airport, killing dozens of people and wounding many others, Turkish officials said Tuesday. (Photo by Emrah Gurel/AP Photo)

The hull on a boat that carried Rohingya migrants for three months is seen at Langkawi island, in the Malaysia's northern state of Kedah, Malaysia, May 12, 2015. Thailand and Malaysia may set up camps and detention centers to shelter hundreds of refugees arriving on their shores, officials said on Tuesday, as a leading inter-governmental agency said about 7,000 boat people were still adrift in the Bay of Bengal. (Photo by Olivia Harris/Reuters)