When the % change is 8.4, what is the population rank?
CREATE TABLE "references" (
  "name" text,
  "2011_census" real,
  "2006_census" real,
  "pct_change" text,
  "land_area_km" text,
  "density_pop_km" text,
  "population_rank" real
);
SELECT MIN("population_rank") FROM "references" WHERE "pct_change"='8.4';