On my old Steinway, the lowest key that doesn’t have a damper is the second-highest E. On a Bösendorfer I got to play recently, I noticed that the highest key without one was (I believe) the second-highest G. What note most commonly is the highest without a damper on major companies’ pianos?
Steinway grands often cease damping at the same E as yours, because the harp's rightmost rib blocks where the E's damper would be. Many harped pianos (Baldwin, Kawai, Kimball) transition one note higher, at the F.
@Tim's comment is right, there's no industry standard. It's just convergent design, that as you go up in pitch, eventually dampers aren't worth the bother. A more precise enumeration could come from visiting some big piano showrooms and inspecting individual instruments, but it wouldn't affect many people's buying decisions.