Subject	Before	After	Difference
1	81	78	3
2	87	91	-4
3	86	78	8
4	82	78	4
5	90	84	6
6	86	67	19
7	96	92	4
8	73	70	3
9	74	58	16
10	75	62	13
11	72	70	2
12	80	58	22
13	66	66	0
14	72	60	12
15	56	65	-9
16	82	73	9