From a resource standpoint, the important point of this comparison is that including the marginal external costs of production and allocating resources based on the full social cost results in a higher price for the good (Ps > Pp) and less output (Os < Op) than only including the private costs.
Today, the nation's farmers are 17 years older than the average American worker, with the ranks of farmers who are 75 years and up outnumbering those in their prime working years of 35 to 44. One big reason U.S. farmers are going gray: spiraling costs.
No one knows for sure, but because bull markets age in what you might call dog years, if it were a human it would be very, very, very old. The average American lifespan, despite a slight decline recently, is about 79 years, or 948 months. The average age of a bull market, meanwhile, is 57 months. So, if you assume that every bull-market year is equivalent to about 16.6 human years (948 months divided by 57 months), this eight-year-old bull market is actually 133 years old. (The oldest person on Earth is currently 117.)