What is the average rating for a Flyde that has a Burnley less than 0?
CREATE TABLE "summary_of_results_2005" (
  "party" text,
  "burnley" real,
  "chorley" real,
  "fylde" real,
  "hyndburn" real,
  "lancaster" real,
  "pendle" real,
  "preston" real,
  "ribble_valley" real,
  "rossendale" real,
  "south_ribble" real,
  "west_lancashire" real,
  "wyre" real,
  "total" real
);
SELECT AVG("fylde") FROM "summary_of_results_2005" WHERE "burnley"<0;