SELECT COUNT(founded) FROM table_26218124_1 WHERE stadium = "Westfalenstadion"
CREATE TABLE table_26218124_1 (founded VARCHAR, stadium VARCHAR)
มีกี่สโมสรที่ก่อตั้งขึ้นในสนามกีฬาเวสต์ฟาเลนสตาดิโอน?
How many clubs were founded in the westfalenstadion stadium?