Table:
1991 cohort
2006 cohort

model 1
model 2
model 3
model 1
model 2
model 3

coefficient

canadian-educated immigrants
0.210
0.177
-0.208
0.072
0.250
-0.138

years since the base year
0.133
0.114
0.114
0.124
0.176
0.180

squared years since the base year
-0.005
-0.004
-0.004
-0.006
-0.016
-0.016

canadian-educated immigrants interacted with years since the base year
0.012
0.001
0.004
0.081
-0.020
-0.007

canadian-educated immigrants interacted with squared years since the base year
0.000
0.000
0.000
-0.008
0.003
0.002

age in the base year
..
0.084
0.076
..
0.103
0.091

age squared
..
-0.002
-0.001
..
-0.002
-0.002

graduate degrees
..
0.246
0.203
..
0.070
0.060

months of study in a year
..
-0.150
-0.141
..
-0.091
-0.086

french
..
-0.161
-0.150
..
-0.075
-0.072

other languages
..
-0.299
-0.301
..
-0.265
-0.263

visible minorities
..
-0.282
-0.276
..
-0.105
-0.076

atlantic region
..
0.111
0.116
..
0.154
0.130

quebec
..
-0.177
-0.162
..
-0.213
-0.161

manitoba and saskatchewan
..
-0.103
-0.094
..
0.007
0.007

alberta
..
-0.018
-0.025
..
0.247
0.228

british columbia
..
-0.194
-0.180
..
-0.036
-0.037

regional unemployment rate
..
-0.028
-0.028
..
-0.032
-0.036

other economic class
..
-0.096
-0.068
..
-0.147
-0.117

family class
..
-0.196
-0.159
..
-0.233
-0.177

refugees
..
-0.180
-0.183
..
-0.422
-0.389

origin-country tertiary education quality
..
-0.004
-0.002
..
0.000
0.000

origin-country log gross domestic product per capita
..
0.053
0.041
..
0.050
0.044

origin-country official language english
..
0.187
0.119
..
0.139
0.103

origin-country official language french
..
0.102
0.109
..
0.039
0.075

low prior earnings
..
..
0.110
..
..
0.221

medium prior earnings
..
..
0.288
..
..
0.539

high prior earnings
..
..
0.690
..
..
0.972

years of prior canadian work experience
..
..
0.023
..
..
0.012

years of canadian study
..
..
0.015
..
..
-0.020

intercept
9.788
9.124
9.319
10.075
8.796
8.956

Given a table image, please tell me which table cells are merged cells. Return the merged cell regions in the JSON format of {'top-left':(x, y), 'bottom-right':(m, n)}, where (x, y) and (m, n) represent the (row_id, column_id) coordinates of top-left cell and bottom-right cell, respectively. The row_id and column_id are numberd from 1.

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