This is true, for the US. It is also one of the symptoms of what is wrong with "enforcement" in that country.
Police officers in many other countries (such as Germany for instance) are explicitly instructed to shoot to wound if at all possible - and with good results both in terms of getting their suspects arrested but not killed, and in terms of not getting killed themselves. Indeed, this is not just the case for police worldwide, but even for the US armed forces when working under "nation building" rules of engagements rather than "total war" rules of engagements.
A shoot-to-kill doctrine is an obvious sign that rather than having an attitude of serving and protecting their community, the enforcers are serving/protecting themselves first.
And obviously this is not an isolated incident hence much of the anger directed at police. Guns should be last resort but sadly is not the case today.
[1] http://heavy.com/news/2015/12/san-francisco-sfpd-police-shoo...
So if that's true why isn't information gathered about every single round of ammunition that's fired? Because every time that trigger is pulled is a time when someone (the officer, a member of the public) is at risk of death, and pulling the trigger carries a very real risk of killing the alleged perpetrator. (Or innocent bystanders).
It's baffling to me that statistics like these are not kept.
Maybe this would be too high a burden. But at least they should keep numbers on how many people they kill, and what the precise situation was around that death.