I still think that data represents simply which countries found out first about sci-hub. There was a science article showing that it's used nearly everywhere now, because it's actually easier to use
I guess up to a point that's also the case, but it's harder to quantify when they found out about it. And sure, it's used basically world-wide by now, but there are still inter-country differences that aren't only explained by the time people learned about sci-hub :-)