Keep in mind when looking at data like this that we do not actually know how many people police kill. Despite the 1994 crime bill mandating the detailed reporting of every police killing to the feds no one has ever forced them to do it. What we are seeing are only the ones that ended up having an outside entity involved in the investigation (be it of the crime leading to the killing or of the killing it's self).
Years ago, in an interview with a an industry rag Patrick Hendry, head of the NY police union, the largest of it's kind, was asked about this and he answered that "most" killings never leave the department that employed the officer(s) who committed the homicide.
https://fivethirtyeight.com/features/how-many-americans-the-police-kill-each-year/