It is probably still almost 10%, but we seem to imply that "frequency of a pin within the set of all 4 digit pins" is frequency of the pin amongst the populatio

It is probably still almost 10%, but we seem to imply that "frequency of a pin within the set of all 4 digit pins" is frequency of the pin amongst the population, but that means we're not counting people who, e.g., use 6 digit pins. (Or I suppose that just reinforces the point: most people are setting first 2 digits of the 6 digit pin to "00", essentially, although now I wonder if a phone accepts 001234 and 1234 as equivalent. Is it a string, or an int? I'd presume the former…)