From this month's CTU Economic Bulletin [PDF]:
This is a revised version of the graph, using a more recent series of the top 1% income share, but it tells the same story: unionization is correlated with equality, and deunionization with inequality. And with good reason: if workers are able to organise and bargain collectively, they are more able to gain a fair share of growth, and resist the erosion of their living standards by the greedy rich.
At this stage, its worth remembering that National are planning further attacks on workers' rights in an effort to crush unions even further. Their rich mates will do very well out of that. As for the rest of us, we'll be left with an even more unequal and unjust society.