Although the Demographics screen isn’t really useful, many people are curious as to what those numbers really mean. Many people had theories and could figure out by themselves how some of them were figured. Here is my analysis after extensive testing in the debug mode for PTW:
Approval rating: This one’s easy. The percentage of your people that are happy. If every single person is happy, you have 100%. If everyone is content it is 50%. Edit: This can be misleading when you get specialists, because the specialists count as only content people. So even if everyone is happy or an entertainer, you won’t have 100% approval rating if you have any specialists.
Population: Add up all the population you get from the city view from all your cities. Not population points, like size 1, 2 or 3, etc. but the 10,000 or 100,000 you see under the city name.
GNP: Total gold in all your cities before corruption takes a bite out of it.
1 gold= 1 million
Mfg. Goods: Total unwasted shields in all your cities.
1 shield = 1 megaton.
Land Area: # of tiles in your territory * 100.
1 Tile =100 square miles
Sea is included in this, but does not help in the territory part of your game score.
Literacy: % of your citizens who live in a city with a library, university, AND research lab. If every city has just a library you will have 33%, because they are missing the other 2 science buildings.
Edit: Or live in a city with 1 or more scientific Great Wonders (Great Library, Newtons, SETI, Theory of Evolution, Cure for Cancer, and Internet) Copernicus’s does not count because despite it helps science, it isn’t given the scientific flag. Having 1 of those wonders counts the same as if they had all the other improvements in the city. Two small wonders (Apollo and Intelligence Agency) give you credit for having 50% science in that city. You also get 3% added to your literacy rate when you get the literature tech. No bonus when you get education. Great Library still helps your literacy rate even after it is obsolete.
Disease: % of the tiles in your territory that is floodplains or jungle.
Pollution: # of tiles that are currently polluted.
Life expectancy: % of your citizens who live in a city with a granary, aqueduct, AND hospital. Minimum is 20, maximum is 99.
Family Size: The average amount of excess food that each city is producing/2. If you have 1 city that is producing 4 extra food, that 4 food would feed 2 people, so your family size would be 2 children. Minimum is 1, hard to say exactly what the max would be. In most cases you won’t see this above 2, maybe 3 or 4 if all your cities are extremely rich in food, experiencing a very fast growth period or just put down a alot of railroads on irrigated tiles.
Military Service: 10 years * # of military units / # of citizens. Military units are units with an attack and defense value, so workers, scouts and princesses don’t count. Kings do. So at the start of a mass regicide game you will have a military service of 70 years because of the 7 military units *10 years divided by just your 1 citizen. 0 years if you have no army or you have just a few units, but thousands of population points.
Annual Income: The number of connected strategic/luxury resource types in your territory. The minimum value is 1 and you get a +1 bonus for your first trade route with another civ. Thanks DaveMcW
Productivity: The total amount of uncorrupted gold, unwasted shields, and excess food you are producing in all your cities.