The enumerated population rate shows what share of the total population in dwellings lives in a given dwelling type. It is the enumerated population for that dwelling type divided by the total enumerated population across all types.
The figures come from Census data collected by the Australian Bureau of Statistics. From the jump-off year on, the rate is carried forward from the Census year.
A rising rate means a growing share of people live in that dwelling type. A falling rate means the share is shrinking.