user: Question: On which date did Michael Signer earn 4%?
Columns: ['Source', 'Date', 'Jody Wagner', 'Pat Edmonson', 'Michael Signer', 'Rich Savage', 'Jon Bowerbank', 'Undecided']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Public Policy Polling', 'June 6–7, 2009', '41%', 'n/a', '12%', 'n/a', '6%', '42%']
SQL:

assistant: SELECT "Date" FROM "Table" WHERE "Michael Signer" = '4%';