user: Question: When was the film directed by Pen-Ek Ratanaruang released?
Columns: ['Date', 'Title', 'Director', 'Production Cost', 'Singapore Gross']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['2004', '2004', '2004', '2004', '2004']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Director" = 'Pen-Ek Ratanaruang';