Imagine if you were born in 1900. You'd have a 23% chance of dying before age 20 (a 13% change before age 1). You'd have a 38% chance of dying before age 45 (see first two graphs below).

Compare that to kids born recently. You'd have about a 1% chance of dying before age 20, and about a 4% chance of dying before age 45. A dramatic change over the last century.

How would this effect your behavior? If you were born in 1900, you'd want to get married early, and have plenty of children. If you were born recently, you'd probably take your time - get married later, have fewer children - and education would be more valuable (because you'd probably live longer).

So we'd expect to see more young people stay in school, and more older people stay in the work force - and that is exactly what is happening.

Some people look at these trends and worry about supporting all the old people. To me, this is all great news - the vast majority of people can look forward to a long life - with fewer people dying in childhood or during their prime working years.

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