Table:
characteristic
2008
2009
2010
2011
2012
2013
% change

2012-13
2008-13

all graduate students in surveyed fields
529275
545685
556532
560941
561418
570300
1.6
7.8

full-time enrollment
383560
398498
409107
411168
414384
424508
2.4
10.7

first time
108819
115755
118492
120135
121856
127725
4.8
17.4

part-time enrollment
145715
147187
147425
149773
147034
145792
-0.8
0.1

male
297278
307936
316051
318209
318870
324913
1.9
9.3

female
231997
237749
240481
242732
242548
245387
1.2
5.8

u.s. citizens and permanent residentsa
369781
382342
390403
392160
385343
381225
-1.1
3.1

full-time enrollment
245691
256503
263871
262043
258477
256211
-0.9
4.3

first time
68093
75321
77242
75394
73704
72731
-1.3
6.8

part-time enrollment
124090
125839
126532
130117
126866
125014
-1.5
0.7

hispanic or latino
26098
27265
28609
30808
31406
32819
4.5
25.8

not hispanic or latino

american indian or alaska native
2618
2549
2500
2392
2188
2198
0.5
-16

asianb
30356
31754
32185
33147
32700
32917
0.7
8.4

black or african american
28680
29973
31094
32197
31338
30911
-1.4
7.8

native hawaiian or other pacific islanderb
1121
1125
1088
1008
920
882
-4.1
-21.3

white
242623
250443
255256
256096
250783
246518
-1.7
1.6

more than one raceb
1319
2300
4989
6103
7578
8015
5.8
507.7

unknown ethnicity and race
36966
36933
34682
30409
28430
26965
-5.2
-27.1

temporary visa holders
159494
163343
166129
168781
176075
189075
7.4
18.5

full-time enrollment
137869
141995
145236
149125
155907
168297
7.9
22.1

first time
40726
40434
41250
44741
48152
54994
14.2
35

part-time enrollment
21625
21348
20893
19656
20168
20778
3
-3.9

A table may have multiple merged cells and we can represent a merged cell region by a JSON {'top-left':(X1, Y1), 'bottom-right':(X2, Y2)}. Here, '(X1, Y1)' and '(X2, Y2)' denote the coordinates (row_id, column_id) of the top-left and bottom-right cells of the merged regions, respectively. Now, based on the shown table image, please find all merged cells in this table and return their representations in the above format. Keep in mind that row and column IDs start from 1.

The merged cell regions are as follows:
{'top-left':(1, 1), 'bottom-right':(2, 1)}
{'top-left':(1, 2), 'bottom-right':(2, 2)}
{'top-left':(1, 3), 'bottom-right':(2, 3)}
{'top-left':(1, 4), 'bottom-right':(2, 4)}
{'top-left':(1, 5), 'bottom-right':(2, 5)}
{'top-left':(1, 6), 'bottom-right':(2, 6)}
{'top-left':(1, 7), 'bottom-right':(2, 7)}
{'top-left':(1, 8), 'bottom-right':(1, 9)}.