In most countries the gender pay gap has decreased in the last couple of decades

See Six key facts about the gender pay gap by Esteban Ortiz-Ospina of Our World in Data. Excerpt:

"How is the gender pay gap changing over time? To answer this question, let's consider the following chart, showing available estimates from the OECD. These estimates include OECD member states, as well as some other non-member countries, and they are the longest available series of cross-country data on the gender pay gap that we are aware of.

Here we see that the gap is large in most OECD countries, but it has been going down in the last couple of decades. In some cases the reduction is remarkable. In the UK, for example, the gap went down from almost 50% in 1970 to about 17% in 2016.

These estimates are not directly comparable to those from the ILO, because the pay gap is measured slightly differently here: The OECD estimates refer to percent differences in median earnings (i.e. the gap here captures differences between men and women in the middle of the earnings distribution); and they cover only full-time employees and self-employed workers (i.e. the gap here excludes disparities that arise from differences in hourly wages for part-time and full-time workers).

However, the ILO data shows similar trends for the period 2000-2015.

The conclusion is that in most countries with available data, the gender pay gap has decreased in the last couple of decades."