A Chicago City Hall’s inspector general released a report Thursday that questioned why a relatively small percentage of black applicants are hired by the Chicago Police Department compared to white applicants.

“It is the disproportionately high attrition of black candidates throughout the hiring process, not a lack of applicants, that is most responsible for the low number of black police officers ultimately hired,” according to the report from Inspector General Joseph Ferguson’s office.

The report said the Chicago Police Department needs to reevaluate its hiring practices for bias and “assess whether the tests and standards at each stage validly select for job-relevant skills and abilities,” Chicago Sun-Times.

The inspector general examined the results of former Mayor Rahm Emanuel’s 2016-2018 police “hiring surge” and found that black candidates represented 37% of the applicants but only 18% of those invited to the police academy.

They were more likely to fail the written exam, background check and psychological evaluation than applicants of other races.