Actual lengths of stay at a hospital's emergency department in 2009 are shown in the following table(rounded to the nearest hour).Length of stay is thetotal of wait and service times. Some longer stays are also approximated as 15 hours in this table.

1- Hours: from 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 1 0 , 11 , 12 , 13 , 14 , to 15

2- Count: 19, 51 , 86 , 102 , 87 , 62 , 40 , 18 , 14 , 11 ,10

3- Percent: 3.80, 10.20 , 17.20 , 20.40 , 17.40 , 12.40 , 8.00 , 3.60 , 2.80 , 2.20 , 2.0

Calculate the probability mass function of the wait time for service ?