In this country, the arrest rate per 100,000 residents is 3888.2. That means that over 2-1/2 million arrests are made each year. In making those arrests, a police officer never knows if the person being arrested will attempt to kill him/her or not; even during a routine traffic stop.
According to the Bureau of Justice Statistics, nearly 20% of all inmates in state prisons were armed at the time of arrest. For federal prisoners, the rate is 15%. Often, the decision whether or not to use deadly force is made in a split second. And yes, there will be mistakes, and unarmed people will die. Whether its a young boy with an air gun that had its normally identifying orange tip removed or, a woman pulling out a cell phone at the wrong time.
So, here are the stats on police killings as of this writing.
According to a website run by The U.K. Guardian called 'The Counted', through November 15th, a total of 964 persons were killed by U.S. police in 2015. 20% of those (190) were unarmed at the time of their death. Also understand that we don't know the circumstances surrounding those 190 deaths and whether or not the police personnel causing them were found to be guilty of murder, or whether or not the deaths were deemed accidental or justified. For example, 47 of those 190 deaths were as a result of being tasered; a supposedly non-lethal tool for cops to use when someone is resisting arrest.
To me, Quentin Tarantino's charge that cops are "murderers" is totally unfounded. Given the number of times the police have had to arrest someone committing a crime -- 2-1/2 million times -- the number of unarmed deaths-by-cops is extremely small. This proves that U. S. cops are showing relative restraint before using deadly force. And, where is the gratitude from Tarantino for the 2-1/2 million arrests made while enforcing the law, putting themselves in jeopardy, and keeping people safe?
Pressure is on Tarantino to apologize for calling cops murderers: http://nypost.com/2015/11/02/quentin-tarantino-to-apologize-for-calling-cops-murderers/
The Counted: Numbers Killed By Police: http://www.theguardian.com/us-news/ng-interactive/2015/jun/01/the-counted-police-killings-us-database#
Fatal shooting of teen with toy gun was reasonable, experts say: http://nypost.com/2015/10/11/fatal-shooting-of-teen-with-toy-gun-was-reasonable-experts-say/
Uh Oh! Not Again! Unarmed Black Woman Shot to Death by Police in Georgia!: http://newsbuzzdaily.com/uh-oh-not-again-unarmed-black-woman-shot-to-death-by-police-in-georgia/
Arrest Rate in U.S.:https://www.google.com/search?q=number++of+arrests+per+year&ie=utf-8&oe=utf-8
Bureau of Justice: Firearm Use by Offenders: http://bjs.gov/content/pub/pdf/fuo.pdf