We can do better than anecdote. 74% of the largest tech firms executives are white [1]. This perfectly reflects 1990 demographics, when the US was 76% white [2]. A 30 year lag between arriving to a country, and becoming an executive, seems more than reasonable.

[1] https://phys.org/news/2018-06-diversity-silicon-valley-tech-... - using weighted average of the histogram.

[2] https://en.wikipedia.org/wiki/Historical_racial_and_ethnic_d...