I'll comment briefly on your question. It is true. You're right that some of our exchanges in this discussion suggest that something happens suddenly at one point, but of course it's a life-course factor.
Aging starts at birth, as it is, and there's a difference between the aged and aging. We are preparing for active aging even when we're kids. For instance, if we have concussions playing hockey, they could be associated later in life with increased susceptibility to developing Alzheimer's disease.
You're right: these figures were only snapshots of those at ages 55, 65, and 85, but this is a long, life-course perspective.