City workers walk past the Bank of England in the City of London, Britain, March 29, 2016. REUTERS/Toby Melville/File Photo

Passers-by are reflected on a signboard displaying currency signs outside a bank in Tokyo November 27, 2014. REUTERS/Issei Kato/File Photo

Iraqi soldiers fire a rocket toward Islamic State militants on the outskirts of the Makhmour south of Mosul, Iraq, March 25, 2016. REUTERS/Azad Lashkaril/File Photo

A student who escaped when Boko Haram rebels stormed a school and abducted schoolgirls, identifies her schoolmates from a video released by the Islamist rebel group at the Government House in Maiduguri, Borno State May 15, 2014. REUTERS/Stringer/File photo

Milorad Dodik, President of Republika Srpska is pictured on an election poster calling for votes for a referendum on their Statehood Day in Prnjavor, Bosnia and Herzegovina, September 21, 2016. Picture taken September 21, 2016. REUTERS/Dado Ruvic

An election poster calling for votes for a referendum on their Statehood Day is pictured in Prnjavor, Bosnia and Herzegovina, September 21, 2016. Picture taken September 21, 2016. REUTERS/Dado Ruvic

Milorad Dodik, President of Republika Srpska is pictured on an election poster calling for votes for a referendum on their Statehood Day in Prnjavor, Bosnia and Herzegovina, September 21, 2016. Picture taken September 21, 2016. REUTERS/Dado Ruvic

Rosetta, the European Space Agency's cometary probe with NASA contributions, is seen in an undated artist's rendering. REUTERS/ESA/NASA/Handout