There are more displaced people in the world than at any point since World War II

More than 60 million people had been forcibly displaced from their homes at the end of 2015, the highest number of displaced people since World War II.

And most of them remain in their own countries, rather than seeking asylum elsewhere, according to Pew data newly compiled from the United Nations.

The data show that 37 million individuals were categorized as people forced to leave their homes but still living inside their birth country. Here’s the key graph, which shows the spike in those forcibly displaced but still within their home nation:

“Many displaced people do in fact prefer to stay in their own country and many will move many times within their own borders before taking the decision to leave, “Ariane Rummery, senior communications officer for the U.N. High Commission on Refugees, told me by email.

They may go to other parts of the country where they have relatives or where they know people, speak the language and have links, she said, and stay as close to their homes as possible so they can go home as soon as circumstances allow. There is also increasing border control in many areas and some would-be refugees find it harder and harder to leave, she said.

That figure–nearly 2/3 of all displaced persons–represents a huge increase from 20 years ago, when just 20% of all displaced persons were living inside their birth country, Pew says. The top three countries with the largest populations of internally displaced people today are Colombia (6.9 million), Syria (6.6 million) and Iraq (4.7 million).

Colombia has long held the title for most internally displaced persons thanks to the decades-long conflict between the Colombian government and armed Marxist guerillas. But at 12.5 million, Syrians represent the largest recent contributor to the worldwide displaced population (internal or otherwise), suggesting that, even though the number of refugees coming into Europe surged to a record level in 2015, the pipeline remains huge. Here’s a map produced by the U.N. last year showing their flows within Syria. Most have tried to move north, towards Turkey, or east toward Lebanon.

In a report last year, the BBC called the current flow of Syrians into Europe “the tip of the iceberg” of refugees affected by conflict. In fact, they represent just 6% of those fleeing.

“Generally, people try to find solutions within their own countries first,” Erin Mooney who is an expert in displacement and who has worked in Syria, told the BBC.

“Often they want to stay close to their homes to keep an eye on their property, perhaps hoping they’ll one day move back. Now, though, the conflict is into its fifth year and people are becoming much more desperate.”

Some will have lost their documents, so foreign travel is inevitably hard, the BBC says. Others have become besieged in areas that once seemed safe. More often than not, they are simply too poor to leave.

“The journey to Europe is very cumbersome, and it’s not cheap so you have to have a certain level of resources to do it,” Carsten Hansen, Middle East director for the Norwegian Refugee Council, told the BBC.

Overall, 1/5th of the world’s displaced population is now Syrian, Pew found.

Rob covers business, economics and the environment for Fusion. He previously worked at Business Insider. He grew up in Chicago.