Very interesting post! In my experience with my city, I find I hover between a 70-75 percent ratio with regard to population and income. I’ll have to take a look at the cities that do double the income compared to population.
As for the cities with 0 SIM incomes, they seem to have gone for a large population with no corresponding income producing cards. They have a large unemployed population. This wipes out their SIM income plus tends to receive funds from the government tax. Or, at least, this seems to me to be the case.
Thanks. Without looking into it yet, I can't understand why they would choose to have 0 Income. I assume that's intentional or they're just not managing their city at all.