user: Question: What is the air date when the U.S. viewers was 5.50 million?
Columns: ['Series #', 'Episode #', 'Title', 'Directed by', 'Written by', 'U.S. viewers (million)', 'Original airdate', 'Production Code']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [52.0, 1.0, '"The Aftermath"', 'Ian Toynton', 'Josh Schwartz', '7.50', 'September8,2005', '2T6251']
SQL:

assistant: SELECT "Original airdate" FROM "Table" WHERE "U.S. viewers (million)" = '5.50';