Undocumented immigrants have made up roughly 5 percent of the U.S. labor force for the past seven years despite efforts from state and national lawmakers to require employers to better screen job applicants. 

There were 8 million undocumented immigrants working or looking for work in 2014, a figure that has remained largely unchanged since 2009, a report released by the Pew Research Center Thursday found. They join 133 million U.S. born workers and 19.5 million documented immigrants who make up the American workforce. 

The Obama administration has cracked down on employers who hire undocumented immigrants in recent years, but despite concerns among conservative lawmakers about the nation's foreign-born workforce driving unemployment rates, undocumented immigrants generally don't compete with U.S. citizens for jobs because of their skill level, a recent Urban Instittute report found.

"Many immigrants are working different jobs from natives because they have limited English language or technical skills, or because they have insufficient exposure to the U.S. workplace. If undocumented immigrants become authorized to work in the United States, that still may not be enough to increase competition with natives for low-skilled jobs," the report concluded.

There are about 11 millions undocumented immigrants living in the U.S. Many are young people who came to the country to earn high wagers to help their families back home. About 92 percent of undocumented immigrants are aged 18 to 64, compared with 60 percent of U.S.-born population.

"Among unauthorized immigrants, males are more likely than their U.S.-born and lawful immigrant counterparts to be working or looking for work, while female unauthorized immigrants are less likely to be in the labor force," the report concluded.

Undocumented immigrants work largely in the agriculture, construction, leisure and hospitality industries. Some undocumented immigrants were able to legally obtain work permits under President Barack Obama’s 2012 executive action that gave some immigrants certain temporary protections. 

California, Texas and New York, unsurprisingly, had the largest  number of undocumented immigrants workers. Nevada, which attracts large number of hospitality and construction workers, had the most undocumented workers based on total share of the workforce, with 10 percent of its workers being undocumented.