The z score is used to determine the number of standard deviations by which the raw score is above or below the mean. If the z score is positive then the z score is above the mean while for a negative z score implies that it is below the mean. The z score is given by:
For the largest 9%, the score is 100% - 9% = 91% = 0.91
From the normal distribution table, the z score that corresponds to 0.91 is 1.34