From "A distant mirror: The calamitous 14th century" by Barbara Tuchman. And her comments on the death toll and social upheaval brought about by the Black Death (which killed somewhere between 40-60% of the population rich or poor):
Disaster is rarely as pervasive as it seems from recorded accounts. The fact of being on the record makes it appear continuous and ubiquitous whereas it is more likely to have been sporadic both in time and place. Besides, persistence of the normal is usually greater than the effect of the disturbance, as we know from our own times. After absorbing the news of today, one expects to face a world consisting entirely of strikes, crimes, power failures, broken water mains, stalled trains, school shutdowns, muggers, drug addicts, neo-Nazis, and rapists. The fact is that one can come home in the evening--on a lucky day--without having encountered more than one or two of these phenomena. This has led me to formulate Tuchman's Law, as follows: "The fact of being reported multiplies the apparent extent of any deplorable development by five- to tenfold" (or any figure the reader would care to supply).
Survivors of the plague, finding themselves neither destroyed nor improved, could discover no Divine purpose in the pain they had suffered. God’s purposes were usually mysterious, but this scourge had been too terrible to be accepted without questioning. If a disaster of such magnitude, the most lethal ever known, was a mere wanton act of God or perhaps not God’s work at all, then the absolutes of a fixed order were loosed from their moorings. Minds that opened to admit these questions could never again be shut. Once people envisioned the possibility of change in a fixed order, the end of an age of submission came in sight; the turn to individual conscience lay ahead. To that extent the Black Death may have been the unrecognized beginning of modern man.