user: Question: Which Week has Attendance of 51558?
Columns: ['Week', 'Date', 'Opponent', 'Result', 'Attendance']
Types: ['real', 'text', 'text', 'text', 'real']
Sample row: [1.0, 'September 18, 1977', 'San Diego Chargers', 'W 24-0', 51022.0]
SQL:

assistant: SELECT "Week" FROM "Table" WHERE "Attendance" = 51558.0;