user: Question: What is the average attendance against the Expos?
Columns: ['Date', 'Opponent', 'Score', 'Loss', 'Attendance', 'Record']
Types: ['text', 'text', 'text', 'text', 'real', 'text']
Sample row: ['April 4', '@ Padres', '8–2', 'Ashby (0–1)', 27104.0, '1–0']
SQL:

assistant: SELECT AVG("Attendance") FROM "Table" WHERE "Opponent" = 'Expos';