I also quickly thought of bias when I read this, and that concern was reinforced by the bit about substance abuse rates in male-predominant fields of work. I don't think it's a stretch to suggest that has been the case for a very long time.
Another way to interpret the data might be, "When interviewed by researchers, men talked more openly about their feelings than they did a decade ago."
Another way to interpret the data might be, "When interviewed by researchers, men talked more openly about their feelings than they did a decade ago."