How many joined when the enrollment was 1150 in Sioux City, Iowa?
CREATE TABLE "current_members" (
  "institution" text,
  "location" text,
  "founded" real,
  "type" text,
  "enrollment" real,
  "joined" real,
  "nickname" text
);
SELECT "joined" FROM "current_members" WHERE "enrollment"=1150 AND "location"='Sioux City, Iowa';