The wage gap at one point, when women were just entering the labour force, did decrease significantly. But now it's sort of stubbornly staying at approximately the same rate, depending on how you calculate it, whether it's full-time, part-time, the two combined, etc. It is a harder thing to move at this point, but because it's somewhere around the 30% rate, there's still a concerted effort by governments at all levels to try to address the wage gap.
The reasons that explain the wage gap—and there are a number of them, and not a one-solution-fits-all kind of thing—are caregiving, labour-market segmentation, continuing bias and discrimination in the workplace, and women's overrepresentation in part-time work.
To actually address the wage gap at this point would take a number of different kinds of initiatives. I would also add that it's much worse for some women. It's less for women of a certain education level, but if you actually go deeper, it's much worse for some women.