There's a bit more on NewsHub here.
This is basicly like the support graph for Scottish independence, which seems to have become demographicly irresistable. Sadly, Jacinda Ardern - who implicitly claims to be the voice of generational change in New Zealand politics - is pushing the Olds' position of "no change", which is going to become increasingly unsustainable. But if she's not going to push for this, then maybe younger New Zealand should get a Prime Minister who will?