So is depression rampant?
Or is it that we recognize it more... AND we accept it so more people will come out and admit it?
Personally, I'd probably say more or less both, heh. Identifying and acknowledging depressive symptoms has a fair amount less social stigma and more understanding, these days, so people become aware of it or acknowledge it both openly and to themselves. Don't try to hide or deny symptoms quite so much as a matter of course (sometimes for few other reasons than the consequences of doing so aren't nearly so potentially severe, in more/modern developed areas). Stuff like that.
Depression very much was a thing in traditional societies and olden times, it just... wasn't talked about, by and large. Or admitted, even (/especially) to yourself. Misidentified (something approaching intentionally, if perhaps unconsciously, if that makes any sense) often enough, too. So on, so forth. It can be interesting to look at old accounts of stuff through a lens of trying to identify symptoms of depression that are there, 'cause the stuff's littered all over the place if you're paying attention to what's being implied and what's notably
not being said. Dunno if I'd be comfortable saying the rates were roughly even or whathaveyou (we don't really have the records to say, and I'm not going down the evopsych route and trying to pull unicorn blood from stone), but it pretty certainly wasn't particularly
uncommon, so far as psych issues go.
Incidentally, areas or cultures that were known for alcohol (or other sorts of drug) problems is an easy start, especially if you're poking around a family line or whathaveyou. It's not a 100% correlation or anything silly like that, particularly considering the nurture passes down, too, even if there's not overt chemical incentives going on, but families that have a notably unusual incidence of alcoholism
also tend to have a notable incidence of (other) symptoms of depression. They like to feed into each other, heh, so if you're looking for one, looking for the other is a good possible sign.