Mexican cartels have seen a surge in growth in their participating members over the last decade, according to a new study, to the point where they have effectively become the nation’s fifth-largest employer.

Researchers created a mathematical model using homicide, missing persons and incarceration data to track cartel recruitment. Their study, published Thursday in the journal Science, found that some 175,000 people in Mexico are employed by 150 different cartel groups.

The researchers said they hope their study can help analysts and governments who “have long struggled to understand cartels” and find a “better way out of this cycle of violence.”

In the last ten years, 37 percent of known cartel members had been killed or incarcerated, and yet the size of cartels grew. The researchers found they must have recruited nearly 20,000 members a year to make up for losses.

An unrelated report released by the U.S. Drug Enforcement Administration in July estimated that the two largest cartels, Sinaloa and Jalisco New Generation, employed more than 44,800 people. The study’s author, Rafael Prieto-Curiel, a former Mexico City police officer, said his model showed a similar number of 46,000 cartel members in those two groups.

Neither of those numbers might be fully representative of the total number though, the Thursday report said.

“The model only accounts for those directly involved in work that puts them at risk of violence, and not members—such as bankers—who help move and launder cartels’ money,” it stated.

Victoria Dittmar, a researcher for Insight Crime who did not take part in the study, told The Guardian that the numbers depend on the definition of a cartel and what constitutes membership.

“It can be very difficult to say who is a member of a criminal organization and who isn’t,” Dittmar said. “What about a politician that receives money? Or someone who cooperates with the group just once?”

Other researchers have said Prieto-Curiel’s July study is a breakthrough because previous attempts to fight organized crime by the cartels have failed — and the study has shown combatting the crime starts with decreasing the cartels’ ability to recruit new members.

“At least we know we have to focus on that question rather than just sending more money to armed forces and building prisons,” said Carlos Gershenson, a computer scientist at Binghamton University who did not participate in the research. “You need to cut the source of the problem rather than dealing with the consequences.”