WASHINGTON, Dec. 27-- A total of 965 American civilians were shot and killed by U.S. police in 2015, and black unarmed men were six times as likely as whites to be shot dead by police, a report said Sunday.

Among the victims of the police shootings, 564 were armed with a gun, 281 armed with less threatening weapons such as knives, toy weapons or cutting instruments, but 90 were unarmed, according to the Washington Post report.

Only 9 percent of the shootings involved unarmed civilians, but they were disproportionately black, according to the Post's analysis.

Although black men make up only 6 percent of the U.S. population, they account for 40 percent, or 36, of the unarmed men shot to death by police in 2015.

The Post also found that a hugely disproportionate number -- three in five -- of those killed after exhibiting less threatening behavior were black or Hispanic.

The killing of Michael Brown, an unarmed black teenager, by a white police officer in Ferguson, Missouri, in August 2014 exposed the U.S. federal government's failure to track the use of deadly force by police.

This case has also ignited a national debate on excessive use of force by U.S. police and sparked the black civil rights movements Black Lives Matter movement, which has been holding protests across the nation against police killings of black people.

Motivated by the Ferguson shooting, the Post launched a comprehensive project to log every on-duty fatal shooting by U.S. police in 2015. It found that U.S. police nationwide were killing more than twice as many people as the Federal Bureau of Investigation had previously reported.

In most cases, the police officers were not indicted for excessive use of force.

In 2015, only 18 officers were indicted as result of the killings, though it nearly tripled the number in the past decade, which averaged five per year. There were 47 such indictments in the years between 2005 to 2014.

The analysis also exposed the lack of training of police officers in dealing with people with mental illness or in emotional crisis, who accounted for one-quarter of those shot dead by police in 2015. A total of 243 of the police shooting victims were believed to have mental illness or in emotional crisis, it found.

This points to a need for better police training, as more than half of the killings involved police agencies that have not provided officers with state-of-the-art training to de-escalate such encounters, the Post said.