Support

If you think my calculation yesterday out of your reach, let me show you a simpler version:

Let's assume a society has a stable population structure, and the death rate after perinatal period is small. In that case, there should be a equal distribution of all age groups in the community - from infant to elderly.

If most of her citizens begin their working life at the age of 20, retire at 60, and have a lifespan of 80, approximately half of the citizen should be "the working class" (40 years out of 80).

In other words, each working citizen needs to support the living of two.

But no. There is a considerable number of people in the working age but are housewives, unemployed, and disabled; their living also depends on the others.

And each working citizen would therefore need to support the living of three to four people.

PS. This estimation is obviously based on the naive assumption that the age structure of that community is stable - which, in general, asks for a birth rate of 2.5 per couple. In countries with very low birth rate or an one-baby policy, the burden of the working class would be much more heavy.