People could work an average of 1,800-2,000 hours per year until they reach their 50’s, taper off to 1,300-1,500 hours in their early 60’s, and move toward the 500-1,000 range as they approach 70. A hospital nurse, an airplane crew member, or a secondary-school teacher, for example, could work five days a week until her late fifties, four days a week until age 62, three days until age 65, and perhaps two days until age 70.