user: Question: What is the Aggregate of Bayer Leverkusen opponents?
Columns: ['Round', 'Opponents', 'Home', 'Away', 'Aggregate']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['1', 'Keflavik', '2–1', '0–1', '2–2 ( a )']
SQL:

assistant: SELECT "Aggregate" FROM "Table" WHERE "Opponents" = 'Bayer Leverkusen';