The number of people who migrated to foreign countries surged by 41 percent in the last 15 years to reach 244 million in 2015, according to a United Nations study released Tuesday. Of those people, 20 million are refugees. The U.N. is planning a series of meeting to address migration in 2016, including a March 30 gathering in Geneva where countries will be invited to pledge resettlement spots for Syrians fleeing civil war. But while the Syrian refugee crisis has gripped the world's attention, it is but a drop in the sea of international migration.

Here are some highlights from the U.N. report on international migration:

— WHERE ARE MIGRANTS GOING?

The vast majority go to Europe, home to 76 million international migrants in 2015, or two-thirds of the total. By individual country, however, the United States had by far the largest portion of the world's migrants — 47 million, or a fifth of the total. Germany and Russia shared the No. 2 spot with about 12 million each, followed by Saudi Arabia (10 million), Britain (9 million) and the United Arab Emirates (8 million.)

— WHERE ARE MIGRANTS COMING FROM?

The largest portion comes from Asia: about 104 million or 43 percent. While Europe takes in the biggest number of migrants, it also contributes a large number: 62 million, or 25 percent of the total. Latin America and the Caribbean was the third-largest regional source of international migration, with 37 million, or 15 percent. Only 2 percent (4 million) are from North America.

India had the world's biggest diaspora, with 16 million people, followed by Mexico (12 million), Russia (11 million), China (10 million) and Bangladesh (7 million) and Pakistan and Ukraine (6 million each).

— WHO ARE THE MIGRANTS?

They are almost equally divided by gender: 48 percent are women. Not surprisingly, most are working-age. The median age of migrants in 2015 was 39. A significant portion — 15 percent — were under 20 years old. But country populations will not get any younger as a result. The United Nations said international migrants can help ease old-age dependency ratios in some countries but will not halt the long-term trend toward population aging. All major areas of the world are still projected to have significantly higher old-age dependency ratios in 2050.

— WHAT DOES THIS MEAN FOR THE WORLD POPULATION?

The vast majority of the world's people stay put. Migrants made up just 3.3 percent of the global population in 2015, up from 2.8 percent 15 years ago. Still, international migration is growing faster than the world's population, with significant consequences for many regions.

Migrants make up 10 percent of the populations of Europe, North America and Oceania. In North America and Oceania, migrants have contributed to 42 percent of population growth since 2000. It was a different story in Europe, where the population would have declined over the same period had it not been for the influx of migrants. Even if current migration levels continue, Europe's population is still projected to decline over the next 35 years because of its surplus of deaths over births.

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On the Internet:

www.unmigration.org