The total number of illegal immigrants in the U.S. has fallen to its lowest level in more than a decade, the Pew Research Center reported this week.

“There were 10.7 million unauthorized immigrants living in the U.S. in 2016, down from a peak of 12.2 million in 2007,” Pew said, citing government estimates.

Pew found that there has been a “sharp decrease in the number of Mexicans entering the country without authorization,” although around half of illegal immigrants in the U.S. — 5.4 million — are Mexican. The number of unauthorized Mexican immigrants living in the U.S. has declined by 1.5 million since 2007.

Central America, on the other hand, is the only region accounting for more U.S. unauthorized immigrants in 2016 than in 2007, Pew said.

Between 2007 and 2016, the number of unauthorized immigrants from Central America increased by 375,000, and the 1.85 million illegal immigrants from Central America in 2016 came chiefly from three countries: El Salvador, Guatemala, and Honduras.

Pew attributed the decline in the total number of unauthorized immigrants principally to “a very large drop in the number of new unauthorized immigrants, especially Mexicans, coming into the country.”

As the number of unauthorized immigrant workers has fallen, so has their share of the total U.S. workforce over the same period, Pew found.

Pew also found that a significant percentage of illegal immigrants in the U.S. entered the country legally but then overstayed their required departure date. The center estimates that immigrants overstaying their visas probably constituted most of the recent unauthorized immigrant arrivals in 2016.

Follow Thomas D. Williams on Twitter Follow @tdwilliamsrome