> I know. I meant the echoing wavefront seems 10y late : 1935+65 = 2000

Good point. I believe I was thinking about 75. 65 crept in because I was also going to mention that at the beginning of the US Social Security program (1935), the assumption was no one lived much beyond 65.

Here is a table that might cast light on the diagnosis of Parkinson's by age: https://academic.oup.com/view-large/1251178

Note population pyramids for 2000[1], 2010[2], and 2020[3].

[1]: https://www.populationpyramid.net/united-states-of-america/2... [2]: https://www.populationpyramid.net/united-states-of-america/2... [3]: https://www.populationpyramid.net/united-states-of-america/2...

Thank you. Your population links are fascinating.

Going [1]->[2]->[3] shows that the real boom after all is the cohort born around 1960.

> real boom after all is the cohort born around 1960.

There is a boom in birth rates which remains sustained high for about 10 years. However, the conditions of early childhood environment keep improving along with a reduction the hazard of early death. The 1945 cohort does end up being hit by the Vietnam war whereas people born in the 60s do not face any of that.

Population numbers reflect who survived.