user: Question: What is the production code for the episode that had 9.18 million viewers (U.S.)?
Columns: ['No.', '#', 'Title', 'Directed by', 'Written by', 'U.S. viewers (million)', 'Original air date', 'Production code']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'text', 'real']
Sample row: [80.0, 1.0, '"High Exposure"', 'Alex Zakrzewski', 'Nicolas Falacci & Cheryl Heuton', '8.21', 'October3,2008', 501.0]
SQL:

assistant: SELECT "Production code" FROM "Table" WHERE "U.S. viewers (million)" = '9.18';