Because there isn’t one.
Via Washington Post:
FBI Director James B. Comey told a gathering of police chiefs that despite a wave of protests prompted by fatal police shootings of black men and boys, “Americans actually have no idea” about how often police use force because nobody has collected enough data.
Comey praised police officers who he said were serving during “a uniquely difficult time,” but said that the steady stream of videos showing police officers using deadly force — a series of widely seen recordings that have stretched from the death of Eric Garner in New York two years ago to the killing, last month, of Keith Scott in Charlotte — has helped fuel a bleak perception of law enforcement.
“It is a narrative that has formed, in the absence of good information and in the absence of actual data, and it is this: Biased police are killing black men at epidemic rates,” Comey told the International Association of Chiefs of Police on Sunday at the group’s annual conference in San Diego “That is the narrative. It is a narrative driven by video images of real misconduct, possible misconduct, and perceived misconduct.”