Europe is currently home to somewhere between 3.9 and 4.8 million illegal immigrants, according to a new survey by the Pew Research Center.

“Europe has experienced a high level of immigration in recent years, driving debate about how countries should deal with immigrants when it comes to social services, security issues, deportation policies and integration efforts,” Pew notes in its latest study of the question.

“Among these recently arrived immigrants are many who live in Europe without authorization,” the article adds. “Coupled with unauthorized immigrants who were already in Europe, their numbers reach into the millions, though together they make up a small share of Europe’s total population.”

Although the number of illegal migrants in Europe reached its peak in 2016, it has fallen only slightly since then, since Europe has so far been unable to devise an effective system for repatriating those migrants whose appeals for asylum have been rejected. The reason that the number has dropped at all is not because the migrant population has decreased but because many “have been approved to remain in Europe.”

Between 2014 and 2017, Pew reveals, Europe’s illegal migrant population climbed from 3.0-3.7 million to 3.9-4.8 million, a significant increase by any measure.

Illegal immigrants now make up just under 20 percent of Europe’s roughly 24 million foreign nationals, meaning that nearly one in five foreigners living in Europe is doing so without authorization.

According to Pew, nearly one quarter of Europe’s unauthorized immigrants are asylum seekers who are still awaiting a decision on their pending application.

Most of these “entered their country of residence without permission,” Pew states, “and the majority of applicants are now seeing their applications rejected.”

In its current study, Pew defines unauthorized immigrants as “people living without a residency permit in their country of residence who are not citizens of any European Union or European Free Trade Association (EFTA) country.”

“Most unauthorized immigrants entered an EU-EFTA country without authorization, overstayed a visa, failed to leave after being ordered to do so or have had their deportation temporarily stayed,” the article notes.

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