I lumped modern and sci-fi together as sci-fi generally sticks close to modern considerations. Whether the food comes from Mars or Argentina, cities would likely develop in a similar manner to modern, but the support values for the various industries would be similar enough to modern that one could tweak the values to what ever degree they needed to come up with their level of development in sci-fi. I just know there are services and industries in existence today that weren't in the medieval world, such as groceries, fuel stations, and power plants. I wouldn't even know where to begin in considering a rough number of their support values. And, yes, I know that power-plants would likely increase in sci-fi, but having a modern base-line would be helpful to work with.