It of course would depend on what roles and geographies you include, but from personal anecdata, I'd say that about 50% of developers I've worked with have taken 'some' university-level maths. And amongst these, there's of course significance variance in backgrounds. Again from anecdata, the best at applying maths to programming are physics majors, who seem to often recognize that a software system exhibits some dynamics, and that they could find (or build) some relatively simple model that would explain and predict that behavior.