After a police officer killed George Floyd on a Minneapolis street corner in 2020, millions of people flooded the streets of American cities demanding an end to brutal police tactics that too often proved fatal to those in custody.

Yet five years later, despite the largest racial justice protests since the civil rights era of the 1960s and a wave of measures to improve training and hold officers more accountable, the number of people killed by the police continues to rise each year, and Black Americans still die in disproportionate numbers.

Last year, the police killed at least 1,226 people, an 18 percent increase over 2019, the year before Mr. Floyd was killed, according to an analysis by The New York Times drawing on data compiled by The Washington Post and the nonprofit Mapping Police Violence. The vast majority of such cases have been shootings, and the vast majority of the people killed were reported to be armed. But police officers, as in the past, also killed people who had no weapon at all, some in the same manner as Mr. Floyd: pinned down by an officer and yelling, “I can’t breathe.”

Among them was Frank Tyson, an unarmed Black man in Canton, Ohio, who uttered Mr. Floyd’s famous words last year before dying when he was wrestled to the ground in a bar by police officers. This happened even though police departments around the country, especially in the aftermath of Mr. Floyd’s murder, have known about the dangers of asphyxiation when keeping a suspect in the prone position. (Two officers were charged with homicide in Mr. Tyson’s death.)