Afghan National police officers demonstrate their training during a visit by U.S. Brigadier General Christopher Bentley to an Afghan National police installation in the Nangarhar province of Afghanistan December 16, 2014. (Photo by Lucas Jackson/Reuters)

A pro-Russian separatist stands guard in front of a building damaged during fighting between pro-Russian rebels and Ukrainian government forces near Donetsk Sergey Prokofiev International Airport, eastern Ukraine, December 16, 2014. (Photo by Maxim Shemetov/Reuters)

A Sierra Leonean man in costume poses on a street in Freetown, Sierra Leone, December 16, 2014. (Photo by Baz Ratner/Reuters)

Sergio Ramos of Spain's Real Madrid celebrates after scoring against Mexico's Cruz Azul during their semi-final soccer match in FIFA Club World Cup at Marrakech stadium December 16, 2014. (Photo by Youssef Boudlal/Reuters)

Juggler Cabalita participates in a parade to celebrate the circus performers' day in San Salvador December 16, 2014. Circus entertainers participated in a parade organised by the union of circus performers to honor all Salvadoran circus artists. (Photo by Jose Cabezas/Reuters)

A circus perfomer participates in a parade to celebrate the circus performer's day in San Salvador December 16, 2014. (Photo by Jose Cabezas/Reuters)

Juggler Rosita Salvadorena prepares to participate in a parade to celebrate the circus performer's day in San Salvador December 16, 2014. (Photo by Jose Cabezas/Reuters)

The “Aguilas Negras” motorcycle team participates in a parade to celebrate the circus performer's day in San Salvador December 16, 2014. (Photo by Jose Cabezas/Reuters)

A soldier looks on during a practise drill in temperatures of about minus 30 degrees centigrade (-22 F) in Heihe, Heilongjiang province, December 16, 2014. (Photo by Reuters/China Daily)

An Ethiopian health worker has her temperature taken upon arrival at Roberts airport outside Monrovia, Liberia, December 16, 2014. Scores of Ethiopian health workers arrived in Liberia on Tuesday to bolster the response to an Ebola outbreak that the government says it wants to stamp out before Christmas. The 87 doctors and nurses will join an African Union (AU) mission against the worst Ebola outbreak on record, which has killed more than 6,800 people in Liberia and neighboring Sierra Leone and Guinea. (Photo by James Giahyue/Reuters)

Magician Yif performs in front of Wanda Movie Park in Wuhan, Hubei province, December 16, 2014. (Photo by Reuters/China Daily)

A man dressed as Father Frost, the Russian equivalent of Santa Claus, walks with Knopka, a Cameroon dwarf goat, through the “Dinosaurs Park”, located in the Taiga area at the Royev Ruchey zoo in the suburbs of Russia's Siberian city of Krasnoyarsk, December 16, 2014. (Photo by Ilya Naymushin/Reuters)

People walk past a model of a dinosaur, with Santa Claus hat and gloves seen on it, at the “Dinosaurs Park” located in the Taiga area at the Royev Ruchey zoo in the suburbs of Russia's Siberian city of Krasnoyarsk, December 16, 2014. (Photo by Ilya Naymushin/Reuters)

Afghan policemen inspect the site of a bomb explosion in Jalalabad, December 17, 2014. A magnetic bomb attached to a police car exploded in eastern Afghanistan, killed two policemen and wounded five other, the provincial spokesman Ahmadzia Abdulzai said. (Photo by Reuters/Parwiz)

An Afghan policeman inspects the wreckage of a police car at the site of a bomb explosion in Jalalabad December 17, 2014. (Photo by Reuters/Parwiz)

Afghan security forces inspect at the site of a suicide attack in Kabul December 18, 2014. One policeman was killed and two were injured on the outskirts of the Afghan capital on Thursday, in a blast caused by a suicide bomber attempting to enter Kabul in a vehicle laden with explosives, an interior ministry spokesman said. (Photo by Omar Sobhani/Reuters)

Indonesian army soldier Partika Subagyo, wearing a costume of the puppet character Bima, dances to raise money for landslide victims, in Solo, December 17, 2014, in this photo taken by Antara Foto. The landslide in Banjarnegara destroyed a village and killed at least 32 people, according to officials. (Photo by Andika Betha/Reuters/Antara Foto)

An employee of SpiceJet Airlines speaks with a passenger at the ticket counter at an airport on the outskirts of Agartala, capital of India's northeastern state of Tripura, December 17, 2014. The parent of India's SpiceJet Ltd said it can't afford to bail out the cash-strapped budget carrier that was forced to ground its entire fleet on Wednesday after creditor oil firms refused to refuel the aircraft. The loss-making airline, majority-owned by billionaire media tycoon Kalanithi Maran's Sun Group, has a fleet of around 22 Boeing Co planes but owes nearly $100 million to a raft of creditors including state-owned oil companies. This week it asked the Indian government for help to keep its aircraft in the air. (Photo by Jayanta Dey/Reuters)

People walk past boards showing currency exchange rates in Moscow, December 17, 2014. The dramatic fall in Russia's rouble slowed on Wednesday, with the government selling foreign currency to prop it up after a 50 percent fall against the dollar this year. (Photo by Maxim Zmeyev/Reuters)

Ksenya, a street musician from a village in Kaluga region, about 160 km. (100 miles) from Moscow, plays guitar to earn money in an underground subway with her daughter in Moscow, Russia, Wednesday, December 17, 2014. She earns about 3000 Rubles (about $ 46 USD) a day and works a few days a month to make ends meet. The Russian government looked at ways of easing the selling pressure on the ruble Wednesday amid fears the country may face a full-blown bank run and as consumers look to buy big-ticket items before prices rise. (Photo by Alexander Zemlianichenko/AP Photo)

A man exits with purchases past a woman begging at a hypermarket in St.Petersburg, Russia, Thursday, December 18, 2014. The Russian economy will rebound and the ruble will stabilize, Russian President Vladimir Putin said Thursday at his annual press conference, he also said Ukraine must remain one political entity, voicing hope that the crisis could be solved through peace talks. (Photo by Dmitry Lovetsky/AP Photo)

Mannequins on the floor outside a shop in an underground passage in Moscow, December 17, 2014. (Photo by Maxim Zmeyev/Reuters)

A woman holds a placard and a candle as she attends a candle light vigil in Kathmandu December 17, 2014, for the students killed at the military-run Army Public School in Peshawar. Pakistan woke up to a day of mourning on Wednesday after Taliban militants killed 132 students in a grisly attack which shocked the nation and put pressure on the government to do more to tackle the insurgency. (Photo by Navesh Chitrakar/Reuters)

Clowns from Slava's Snowshow pose for photographers on London's South Bank, December 17, 2014.The show will take place at London's Royal Festival Hall from December 17 through to January 5, 2015. (Photo by Paul Hackett/Reuters)

A woman walks in the Hay al-Tanak (Tin Neighbourhood) slum in Tripoli, December 17, 2014. The informal settlement has seen an influx of Syrian refugees fleeing the ongoing violence in their country. (Photo by Omar Ibrahim/Reuters)

A Christian worshipper is seen inside the Grotto, where Christians believe Virgin Mary gave birth to Jesus, at the Church of Nativity ahead of Christmas in the West Bank town of Bethlehem December 17, 2014. (Photo by Ammar Awad/Reuters)

A Christian man touches the 14-pointed silver star marking the place where Jesus Christ was born according to Christian tradition, in the “Grotto” in the Church of the Nativity in the West Bank town of Bethlehem, December 16, 2014. Tens of thousands of pilgrims and tourists are expected to flock to Bethlehem to experience Christmas in the town where Jesus was born. (Photo by Jim Hollander/EPA)

Sunni volunteers, who have joined the Iraqi army to fight against militants of the Islamic State, share a meal on the outskirts of Dohuk province December 8, 2014. (Photo by Ari Jalal/Reuters)

A man dressed as a Santa Claus greets Prince Albert II of Monaco (L) as he arrives to attend the traditional Christmas tree ceremony at the Monaco Palace as part of Christmas holiday season in Monaco, December 17, 2014. (Photo by Eric Gaillard/Reuters)

Gerard Depardieu attends a ceremony and news conference to present the watch from the line “Proud to be Russian”, promoted by the actor, in Moscow December 17, 2014. (Photo by Maxim Zmeyev/Reuters)

Actor Gerard Depardieu looks on during a presentation of watches by CVSTOS, a Swiss luxury watch brand from the line “Proud to be Russian” in Moscow, Russia, Wednesday, December 17, 2014. (Photo by Alexander Zemlianichenko/AP Photo)