What is the population density of Siglunes when the change was smaller than -8.1 percent?
CREATE TABLE "list" (
  "name" text,
  "population_2011" real,
  "population_2006" real,
  "change_pct" real,
  "area_km" real,
  "population_density" real
);
SELECT COUNT("population_density") FROM "list" WHERE "name"='siglunes' AND "change_pct"<-8.1;