It actually shows that unionized women earn $6.65 more per hour than women not in a union. As a result, they figured out that $552.5 million per week goes into women's pockets to be used for other things.
The average wage for a unionized woman is $26.32. The average wage for women without a union is $19.16.
What is significant is that unionized women make 84% of what men make, and non-unionized women make 70% of what men make in similar settings.
So there is a significant wage gap.