A number of vehicles were observed passing through a traffic signal during the green phase, with observations as shown in the following table. Calculate the mean, median, and mode of the data. Deduce the shape of the distribution. Determine the MAD(mean absolute deviation), the variance and standard deviation.

Green phase	Number of vehicles	Green phase	Number of vehicles
1	5	16	1
2	7	17	2
3	6	18	6
4	6	19	3
5	4	20	4
6	2	21	5
7	7	22	6
8	8	23	3
9	3	24	1
10	2	25	6
11	4	26	7
12	5	27	2
13	7	28	3
14	6	29	6
15	5	39	6