Table:
undergraduate degree
graduate degree

unadjusted gap
adjusted gap
unadjusted gap
adjusted gap

model a
model b
model a
model b

percent

cohort

2006
-1.9
-1.8
-0.6
-5.8
-3.7
1.7

2007
-0.5
0.6
0.7
-15.8
-13.1
-8.2

2008
..
..
..
..
..
..

2009
-7.6
-7.3
-7.8
-9.8
-8.1
-9.4

2010
-7.7
-7.2
-10.0
-13.6
-9.8
-8.4

2011
-10.1
-8.5
-11.1
-3.2
2.1
0.5

A merged cell in a table can be described using the JSON {'top-left':(A, B), 'bottom-right':(C, D)}. Here, '(A, B)' represents the top-left and '(C, D)' the bottom-right cells' (row_id, column_id) of the merged region. Using the displayed table image, identify all such merged cells in this table and report their locations in the given format. Note that the numbering of both row and column IDs starts at 1.

The merged cell regions are as follows:
{'top-left':(1, 1), 'bottom-right':(4, 1)}
{'top-left':(1, 2), 'bottom-right':(1, 4)}
{'top-left':(1, 5), 'bottom-right':(1, 7)}
{'top-left':(2, 2), 'bottom-right':(3, 2)}
{'top-left':(2, 3), 'bottom-right':(2, 4)}
{'top-left':(2, 5), 'bottom-right':(3, 5)}
{'top-left':(2, 6), 'bottom-right':(2, 7)}
{'top-left':(4, 2), 'bottom-right':(4, 7)}
{'top-left':(5, 2), 'bottom-right':(5, 7)}.