How much is the population density with a GDP at $188,112?
CREATE TABLE "demographics" (
  "country" text,
  "area_km" text,
  "population_2011_est" text,
  "population_density_per_km" text,
  "gdp_ppp_m_usd" text
);
SELECT "population_density_per_km" FROM "demographics" WHERE "gdp_ppp_m_usd"='$188,112';