Who got counted
Picture every U.S. adult of your sex within two years of your age. Each row of the result is the share of that crowd who are at least as tall as you, earn at least as much, or have at least as much schooling. The last row asks for all three at once, so it is always the smallest number.
Why we count instead of multiplying
Many rarity quizzes multiply one share by the next. Income and education tend to rise together, so multiplying them usually makes a person look rarer than the Census records show. We count income and education together in the same 2024 American Community Survey records. Height is measured in a separate CDC survey, so it is the one trait we apply as if it were unrelated to the others at each age.