What is the average Attendance, when Venue is "Candlestick Park", and when Date is "November 25"?
CREATE TABLE "1990s_49ers_17_3" (
  "year" real,
  "date" text,
  "home_team" text,
  "result" text,
  "visiting_team" text,
  "venue" text,
  "attendance" real
);
SELECT AVG("attendance") FROM "1990s_49ers_17_3" WHERE "venue"='candlestick park' AND "date"='november 25';