user: Question: In What Week was the Attendance 75,866?
Columns: ['Week', 'Date', 'Opponent', 'Result', 'Attendance']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'September 1, 1991', 'Atlanta Falcons', 'W 14–3', '74,246']
SQL:

assistant: SELECT "Week" FROM "Table" WHERE "Attendance" = '75,866';