user: Question: How many clubs were founded in the Westfalenstadion stadium?
Columns: ['Name', 'Original Club', 'Stadium', 'City', 'Country', 'Sport', 'Founded', 'Reason for foundation with source']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'real', 'text']
Sample row: ['A.F.C. Liverpool', 'Liverpool F.C.', 'Valerie Park', 'Prescot', 'England', 'Association football', 2008.0, 'Protesting ticket prices at Anfield']
SQL:

assistant: SELECT COUNT("Founded") FROM "Table" WHERE "Stadium" = 'Westfalenstadion';