Well if any of today's American cities lost 5 to 7% of their population in a single year to some sort of medical epidemic I suspect there'd be a fair bit of civil activity.
Well I was going simply off the article. Still, even that entry shows pretty consistent spurts of deaths hitting 3 - 5% of the population so it's pretty consistent with the point of the article (after multiple years of deaths they were force/spurred to act)