Turkey, which hosts the world's largest refugee population, has so far spent $7.6 billion caring for 2.2 million Syrians who have fled strife there, a Turkish deputy prime minister said on Friday. Turkey has been on the front lines of the biggest refugee crisis since World War Two. A record 300,000 or more Syrians and other migrants have arrived in Greece, mostly setting off from Turkey's Aegean coast, according to the International Organisation for Migration.