Lebanon, a small sliver of a country with a population of just 4.5 million people, is also the temporary home of 1 million registered refugees from Syria. That stunning influx gives Lebanon "the highest per capita concentration of refugees worldwide," the U.N. refugee agency told the BBC. The one millionth registered Syria refugee was added to rolls on Thursday, according to the AP

Signing up for aid, 19-year-old Yahya recounted his long ordeal. After being trapped by the fighting for more than two years in his native city of Homs, he was evacuated earlier this year and traveled to Yabroud, a rebel held town near the Lebanese border that soon came under a crushing government offensive.

When staying there was no longer an option, he crossed into Lebanon with his mother and two sisters on March 8. Yahya's father was not with them — he died from sniper fire in Homs in September 2011.

More than 9.5 million Syrians have fled their homes since the beginning of the fighting there a little over 3 years ago, with an estimated 2.6 million becoming refugees in neighboring countries. Lebanon alone registers 2,500 new refugees a day, or more than one person each minute, as the UN noted to the AP. It can take months for a refugee to register with the UN — a necessary step for those who need to receive food rations and other aid from the UN. So, the UN estimates, the actual refugee population —registered and unregistered — in the country could be significantly higher than a million. Many others who have fled Syria, never get registered at all. The secretary-general of the Norwegian Refugee Council Jan Egeland, for instance, told Al Jazeera that the actual refugee population in Lebanon could be "more than half a million" higher. 

As Reuters notes, the refugee population in Lebanon is growing at an astonishing pace. This time last year, the country had 356,000 refugees living there, which itself is a huge number for such a small host country. In other words, about three-quarters of the current refugee population fled to Lebanon in the past year. The World Bank estimates that the refugee crisis has cost Lebanon $2.5 billion in the past year, not even counting the proxy fighting that has taken place inside Lebanon among supporters of the various Syrian factions.