Lots of factors involved....free range vs run vs secure run, especially at night, proximity to wooded areas, amount of rodents and such available to predators, amount of groundcover available to your bird, and even the breeds you keep - more docile birds seem to be easier targets. Like you (knock on wood), I've never lost a bird to a predator. We have woods, but fields surround our immediate property. We have ample field mice and rabbits, based on the "treats" my mostly outdoor cat brings us. We have dogs that'll mark our property. We shut our birds inside a very secure coop at night. And we cross our fingers a lot...lol. We do free range our birds during the day, but they are very good about laying low when hawks are out and about....
I suspect my setup has a lot to do with it. Makes sense though, my barn is in the middle of a field not close to cover for most wild life.