Ending the killing of healthy and treatable shelter pets is a choice; a decision. Some would call it a culture. When a shelter no longer kills savable pets, the ordinary byproduct of that is a save rate or "live release rate" of about 90%. There are some who would say that saving 90% is the focus, as if attaining that number if the goal.
I do not, and cannot, agree. The whole idea is to save those animals who are, well, savable. The end result may be that 98% of animals are saved. The end result may be that 88% of animals are saved if there are a large number who are genuinely suffering, irremediably ill or genuinely aggressive.
So. What's in a number? When we focus on a number as a goal, that means that our culture really has not changed. It means that we make it okay to kill your lost dog or my scared cat as long as we have achieved some number that someone thinks is "enough" as we all pat ourselves on the back and boast about having become "no kill."
We owe it to the animals who end up in our shelters, and our values as a society, to make this about ethics and standards and not about math. To do otherwise completely disregards the entire focus of the no kill movement: to stop destroying animals who were, or who could have been, someone's beloved pet.