CREATE TABLE "overview_of_the_regions" (
  "num" real,
  "name" text,
  "name_english" text,
  "population_2008_07_01" real,
  "area_km" real,
  "pop_km" text,
  "iso_3166_2" text,
  "administrative_centre" text
);

Question: when administrative centre is egilsstaðir, what is the pop./ km²?
SQL: SELECT COUNT("pop_km") FROM "overview_of_the_regions" WHERE "administrative_centre"='Egilsstaðir';

Question: when the name is southern region, what is the administrative centre?
SQL: SELECT "administrative_centre" FROM "overview_of_the_regions" WHERE "name_english"='Southern Region';

Question: when the area (km²) is 22721, what is the pop./ km²?
SQL: SELECT "pop_km" FROM "overview_of_the_regions" WHERE "area_km"=22721;

Question: What is the max pop of 2008 for selfoss?
SQL: SELECT MAX("population_2008_07_01") FROM "overview_of_the_regions" WHERE "administrative_centre"='Selfoss';

Question: When the # is 4, what is the pop./ km²?
SQL: SELECT "pop_km" FROM "overview_of_the_regions" WHERE "num"=4;