It is widely acknowledged that a steady push toward autonomous automobiles is underway. Many new vehicles contain several partial-autonomous features, and a number of near-autonomous or fully-autonomous vehicles are in development for consumer use.
A key example is the Tesla 3, which (along with all future Teslas) will contain "full self-driving hardware", and many speculate could be delivered with full autonomy. Elon Musk has predicted that "Half of all cars in 7 or 8 years will be fully autonomous."
Another detailed report indicates level 4 autonomous cars available at some level from Audi in the late 2020s, from Ford and BMW in 2021, Nissan in 2020, Kia in 2030, Honda at some point, Tesla in 2018, and Volvo in 2017(!).
These could all constitute interesting separate questions, but here we'll ask a combined question inspired by Musk's prediction.
In what year will half of all new automobiles sold in the US be fully autonomous?
For specifics, we'll define "fully autonomous" using the NHTSA "level 4" designation:
The vehicle is designed to perform all safety-critical driving functions and monitor roadway conditions for an entire trip. Such a design anticipates that the driver will provide destination or navigation input, but is not expected to be available for control at any time during the trip. This includes both occupied and unoccupied vehicles.
We'll also specify that "cars" really means "cars," i.e. trucks are excluded. Resolution is by credible industry estimates.