What was the population density in km2 for 2011 in the division where area in km2 was 684.37 in 2011? 
CREATE TABLE "table1_24027047_1" (
  "administrative_division" text,
  "area_km_2011" text,
  "population_2001_census_adjusted" real,
  "population_2011_census_adjusted" real,
  "population_density_km_2011" text
);
SELECT "population_density_km_2011" FROM "table1_24027047_1" WHERE "area_km_2011"='684.37';