What is the Rank of the building that has a Highest floor larger than 50?
CREATE TABLE "list_of_tallest_buildings" (
  "rank" real,
  "name" text,
  "height" text,
  "highest_floor" real,
  "city" text,
  "primary_use" text
);
SELECT "rank" FROM "list_of_tallest_buildings" WHERE "highest_floor">50;