What is the total area of Kruzof island?
CREATE TABLE "islands_km" (
  "rank" real,
  "island_s_name" text,
  "area_sqmi" real,
  "area_km_2" real,
  "location" text,
  "population_2000" text
);
SELECT COUNT("area_km_2") FROM "islands_km" WHERE "island_s_name"='kruzof island';