user: Question: Name the number of opponent with Arrowhead Stadium
Columns: ['Week', 'Date', 'Opponent', 'Result', 'Game site', 'Record', 'Attendance']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'real']
Sample row: [1.0, 'September 8, 1985', 'at Cincinnati Bengals', 'W 28-24', 'Riverfront Stadium', '1-0', 51625.0]
SQL:

assistant: SELECT COUNT("Opponent") FROM "Table" WHERE "Game site" = 'Arrowhead Stadium';