group	date	value
1	2008-01	10
1	2008-04	8
1	2008-07	14
1	2008-10	9
1	2009-01	10
1	2009-04	8
1	2009-07	14
1	2009-10	9
2	2008-01	3
2	2008-04	3.5
2	2008-07	5
2	2008-10	11
2	2009-01	3
2	2009-04	3.5
2	2009-07	4.5
2	2009-10	10.5
3	2008-01	10
3	2008-04	8
3	2008-07	14
3	2008-10	9
3	2009-01	10
3	2009-04	8
3	2009-07	14
3	2009-10	9
4	2008-01	3
4	2008-04	3.5
4	2008-07	5
4	2008-10	11
4	2009-01	3
4	2009-04	3.5
4	2009-07	4.5
4	2009-10	10.5