What is the average capacity for the farm at Gortahile having more than 8 turbines?
CREATE TABLE "proposed_or_under_construction" (
  "wind_farm" text,
  "scheduled" text,
  "capacity_mw" real,
  "turbines" real,
  "type" text,
  "location" text
);
SELECT AVG("capacity_mw") FROM "proposed_or_under_construction" WHERE "wind_farm"='gortahile' AND "turbines">8;