No way that 1,875 people are promoted to L6 every year. I have no idea how he gets from "15% of google engineers are at this level or higher" to 1875 people, a

No way that 1,875 people are promoted to L6 every year. I have no idea how he gets from "15% of google engineers are at this level or higher" to 1875 people, and then on to that many being promoted. I might believe that 1875 is the total number of engineers at L6 or above across the company. Seems slightly low, but not impossible. But I guarantee nowhere near that many are getting promoted every year. Also, making L6 is in no way guaranteed. It takes years.