The Waymo percentage was calculated based on the disengagement rate and a guess at the average speed.

Tesla may be the same or not, but they aren't publishing current numbers where I could find them, only really old numbers.

Not that the exact value matters, because so far as I can tell the only autopilot worse than your threshold was the Uber one that crashed into a pedestrian pushing a bike. Even Tesla's 2016 version beat that.