row	id	grade	ex +	activity +
1	1402135104	9	2	1
2	1402135111	7	2	1
3	1402135116	3.5	2	1
4	1402235105	2	2	0.25
5	1402135118	1.5	2	0.25
6	1402135120	7	2	1
7	1402235108	7	2	1
8	1402235109	5.5	2	0.25
9	1402235113	0	2	0
10	1402235114	3.5	2	0.5