A new report from the Pew Hispanic Center shows the number of illegal immigrants coming to the United States has been steadily decreasing for the past few years.

Pew researchers found that the number of Mexicans illegally entering the country is showing particularly large decreases.

“In 2000 more than three-quarters of a million Mexicans came to the U.S. The vast majority of them came as unauthorized immigrants”, says the Pew Center’s Jeffery Passel. “By 2010 the flows were less than 20 percent what they had been in 2000.”

The reason for the decrease is multi-layered, according to the report. Pew researchers say enforcement at the border as well as in the workplace is driving some of the slow down. But so is the faltering economy.

Additionally, researchers say a decrease in the Mexican birthrate means there are fewer people looking for jobs in both the U.S. and Mexico.

Passel says a strengthening U.S. economy will not bring the number of illegal immigrants back to the numbers seen in the early 2000s.