Dr. Mary Rogowski opens a new margin account at Robinson and Hendricks brokerage firm, which requires a 65% initial margin and a 45% maintenance margin. She purchases 13,000 and stock in Bell Foods using her margin account to the full extent allowable. Prior to any interest being credited on the margin account, by which percentage may the stock fall without Dr. Rogowski's account violating the maintenance margin? Assume that she does not use the margin account for any other purpose and that no interest is credited.