Well, hell, can we trust EffingBI numbers about ANYTHING?

What's not realized is that the FBI count is artificially defined in a way that far undercounts defensive uses. The usual definition of self-defense with a deadly weapon is use of force immediately necessary in light of a reasonable belief that the perp is likely to inflict death or serious bodily injury.

But the FBI UCR Reporting Handbook at pp. 17-18 uses a completely different definition. Reporting officials are instructed, in the case of use of force by a non-LEO, to include under justifiable homicide only killings "The killing of a felon, during the commission of a felony, by a private citizen."

Added by Joe Huffman:
The FBI explicitly states in the UCR Handbook:

Reporting agencies should take care to ensure that they do not classify a killing as justifiable or excusable solely on the claims of self-defense or on the action of a coroner, prosecutor, grand jury, or court.

The coroner, prosecutor, grand jury, and court could unanimously agree it was a justified homicide and the FBI would still insist it not be included in the justified homicide stats.