Name the most overall rank for czech republic
CREATE TABLE "list_by_the_world_health_organization_20" (
  "overall_rank" real,
  "country" text,
  "overall_life_expectancy" real,
  "male_life_expectancy" real,
  "male_rank" real,
  "female_life_expectancy" real,
  "female_rank" real
);
SELECT MAX("overall_rank") FROM "list_by_the_world_health_organization_20" WHERE "country"='Czech Republic';