Roughly, if you are applying to a school where fewer than 40%are admitted, you want to be near top 25% stats to consider it a match, well above top 25% to consider it a safety. No school that admits fewer than 30% applicants can be considered a safety.
If some universities can have a high acceptance rate and be very selective due to the specific (high stats but unique) pool of applicants, universities with low acceptances rates must always be considered as reaches.