A recent survey showed that 91 full-time employees out of a sample of 500 did not use all of their vacation days last year. However, 105 of those studied expressed a desire for more vacation time. Based on this sample, if a full-time employee is chosen at random, what is the probability that he or she is content with the vacation allowance? Express your answer as a fraction in lowest terms or a decimal rounded to the nearest millionth.