user: ### NOW ANSWER:
Question: How many Attendances that has a Visitor of Philadelphia on May 20?
Columns: ['Date', 'Visitor', 'Score', 'Home', 'Decision', 'Attendance', 'Series']
Types: ['text', 'text', 'text', 'text', 'text', 'real', 'text']
Sample row: ['May 15', 'Buffalo', '1 – 4', 'Philadelphia', 'Parent', 17077.0, 'Flyers lead 1–0']
SQL:

assistant: SELECT AVG("Attendance") FROM "Table" WHERE "Visitor" = 'Philadelphia' AND "Date" = 'May 20';