Name the number of date for shea stadium
CREATE TABLE "schedule" (
  "week" real,
  "date" text,
  "opponent" text,
  "time_et" text,
  "tv" text,
  "result" text,
  "record" text,
  "game_site" text
);
SELECT COUNT("date") FROM "schedule" WHERE "game_site"='Shea Stadium';