Originally posted by beest
I think:
Military service is based on ratio of units and population (as stated before). Normally I have a small military and a huge population: military service one year.
Family size indicates wheter or not your population is growing, which depends on how much food your city gets. Much food > ig growth > big families.
I normally get a big amount of data out of the demograpics, about your own civ and the position of your civ against others.