How many electorates are there with Hedmark as a constituency?
CREATE TABLE "by_constituency" (
  "constituency" text,
  "electorate" real,
  "s_spoilt_vote" real,
  "total_poll_pct" text,
  "for_pct" text,
  "against_pct" text
);
SELECT COUNT("electorate") FROM "by_constituency" WHERE "constituency"='Hedmark';