What is the rate of new house construction in Auckland, New Zealand?
If you're really serious about researching this data, I'd suggest contacting the Real Estate Institution of New Zealand: https://www.reinz.co.nz/reinz/public/reinz-statistics/reinz-statistics_home.cfm

As long as there are reasons to move to Auckland (more work etc.) and the supplied housing is not high enough to match the demand, the prices will continue to rise. This effect is visible in many major cities where the supply of housing is (for some reason like goverment rules or slow building) inelastic.