Please explain to me how knowing those values would change the argument. At what thresholds would it make a difference one way or the other?

Please explain how the number you cited is relevant at first place, with the same conditions:

> At what thresholds would it make a difference one way or the other?

You can look at a person and tell that they are bald. You can look at a person and tell that they are not bald. But you can't say exactly when they go from not bald to bald.

Since we can't know how many people are employed as developers, we must guess. But we can reasonably guess that if only 4.25% of the world's population lives in the US, it can't possibly have all the best developers, or even the majority of them.