When the tujia population is 462444 what is the overall percentage of the chinas tujia population? 
CREATE TABLE "by_county" (
  "province" text,
  "prefecture" text,
  "county" text,
  "tujia_population" real,
  "pct_of_chinas_tujia_population" text
);
SELECT "pct_of_chinas_tujia_population" FROM "by_county" WHERE "tujia_population"=462444;