I'm pretty sure Pinker did that exact plot and demonstrated the rate of growth of violent deaths has been considerably less than the rate of growth of the population as a whole. I vaguely recall that deaths from wars (and genocide events) aren't even as big a contributor to the total number of violent deaths as most people assume (obviously in recent decades in developed countries only a tiny percentage of violent deaths have been due to war, but even historically it's not as high as you might imagine).