Joggernot -- Is it possible you're thinking of this:
The most common occupation by state is [not] truck-driver. But for sure, as soon as the first long-haul self-driving truck hits the road it's down to the replacement rate for the fleet as a whole.
Which is OK with me as long as the whole convoy doesn't pull into the left lane to [not] pass a slower vehicle, just as I'm rolling up from behind.