user: Question: What average week number had the Chicago Bears as the opponent?
Columns: ['Week', 'Date', 'Opponent', 'Game Site', 'Final Score', 'Record', 'TV Time', 'Attendance']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'September 1, 1991', 'Miami Dolphins', 'Rich Stadium', 'W 35–31', '1–0', 'NBC 4:15pm', '80,252']
SQL:

assistant: SELECT AVG("Week") FROM "Table" WHERE "Opponent" = 'Chicago Bears';