In addition to this, some folks get Australian citizenship by getting the easier NZ citizenship first, as it's easier for NZ citizens to become Australian citizens. This would add a little bit to the 'percentage overseas' issue.
This is outdated, I believe. These days there is no easy way for NZ citizens to become Australian citizens. However they can still live and work in Australia, but remain second class in various ways, such as not having access to many types of social welfare benefits and not being able to vote.
