user: Question: What was the air date where there were 5.72 million viewers?
Columns: ['No. in series', 'No. in season', '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: [59.0, 1.0, '" Season 4 "', 'Don Scardino', 'Tina Fey', '6.39', 'October 15, 2009', 401.0]
SQL:

assistant: SELECT "Original air date" FROM "Table" WHERE "U.S. viewers (million)" = '5.72';