What is Population in Millions, when GDP 2012 Millions of Euro is 600,638?
CREATE TABLE "economic_variation" (
  "s_member_state" text,
  "gdp_2012_millions_of_euro" text,
  "population_in_millions" real,
  "gdp_ppp_per_capita_2012_euro" text,
  "gdp_nominal_per_capita_2012_euro" text,
  "gdp_ppp_per_capita_2012_eu27_100" text
);
SELECT "population_in_millions" FROM "economic_variation" WHERE "gdp_2012_millions_of_euro"='600,638';