Note the big jump in 1987.It's been upward ever since
This trend needs to be reversed to stop the gap between, those who have more than 1 house and, those who are finding it impossible to have own home.
Modifying Neg Gearing should give gov a win / win situation. Increase in tax revenue without adding further taxes on everyone. Limit neg gearing to new houses to encourage growth in housing supply ,which in turn should bring rent under control.