It's just the number of housing units owned versus rented. The occupancy is ignored in both ownership [even if joinly owned] and rental. As per the definition

It's just the number of housing units owned versus rented. The occupancy is ignored in both ownership [even if joinly owned] and rental. As per the definition: "The householder refers to the person (or one of the persons) in whose name the housing unit is owned or rented"