Castellano vs español - Which countries prefer which?

Question

Suppose we are agreed that for most purposes, "castellano" and "español" refer to pretty much the same language (though perhaps some may disagree---see Is there a difference between "español" and "castellano"? // ¿Hay alguna diferencia entre "español" y "castellano"?).

From reading that other question, I gather that in Spain, "castellano" is today preferred. One answer there also suggests that "Most places use español more but some places including Argentina and Uruguay use castellano more. Places that have a history of suffering under Spanish dominion also seem to prefer to avoid español."

So in which countries is one clearly preferred to the other?

Answer 1

It turns out Wikipedia has an article with a map:

Central America seems to prefer español whereas South America mostly prefers castellano. But I don't know how accurate that map is. If we look at the map's history we see that some countries changed from red to blue or vice versa with no sources given.