Comment by mudetroit

It seems like you are misinterpreting the term housing unit. It isn't the number of buildings. A single apartment in a 200 unit building counts as a housing unit. What this number is telling you is just less than 1 in 5 households in the US live in a building with more than 4 units. I would suspect that the distribution of household size if anything is a bit biased towards single family homes having more people per unit in them if anything.