A Syrian refugee kisses his daughter as he walks through a rainstorm towards Greece's border with Macedonia, near the Greek village of Idomeni, September 10, 2015. [Photo/Agencies]

GENEVA  - More than 1 million refugees and migrants came to the European Union this year, while almost 3,700 died or went missing in perilous journeys which reaped huge profit for smugglers, the International Organization for Migration said on Tuesday.

"This is three to four times as many migrants and refugees coming north as we had in 2014, and the deaths have already far surpassed the deaths last year," IOM chief William Lacy Swing told Reuters.

Almost all those arriving came across the Mediterranean or the Aegean Seas, and half were Syrians fleeing the war. Another 20 percent were Afghans, and 7 percent were Iraqis, IOM and the UN refugee agency UNHCR said in a joint statement.

People smuggling operations probably accounted for the majority of journeys and likely earned at least $1 billion, Swing said, taking "anywhere from $2,000 to maybe $6,000 depending on how many members of the family and depending on which smuggling ring it is".

IOM estimates people smugglers in Europe have made $10 billion or more since 2000, maybe much more. "They are certainly getting very well paid for their services," Swing said.

Out of a total of 1,005,504 arrivals to Greece, Bulgaria, Italy, Spain, Malta and Cyprus by Dec. 21, the vast majority -- 816,752 -- arrived by sea in Greece, IOM said.

IOM spokesman Joel Millman said it was impossible to forecast how the flow of migrants would evolve in 2016.

"So much is in the balance, the resolution of the Syrian war, and the disposition of the European border protection moves that are being contemplated," he said.