user: Question: What date was Joakim Bonnier in the pole position?
Columns: ['Race', 'Circuit', 'Date', 'Pole position', 'Fastest lap', 'Winning driver', 'Constructor', 'Tyre', 'Report']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Monaco Grand Prix', 'Monaco', '10 May', 'Stirling Moss', 'Jack Brabham', 'Jack Brabham', 'Cooper - Climax', 'D', 'Report']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Pole position" = 'Joakim Bonnier';