What proportion of the NZ population was in a council which used Single Transferable Vote for local government elections (as opposed to First Past the Post) at each local government election for the two levels of NZ local government?

Use of STV in NZ council elections

What proportion of the NZ population was in a council which used Single Transferable Vote for local government elections (as opposed to First Past the Post) at each local government election for the two levels of NZ local government?

Unitary authorities are counted for both levels of local government.
Chart: Ben RaueGet the dataCreated with Datawrapper