Table:
period
men
women

hazard ratio
95% confidence interval
hazard ratio
95% confidence interval

from
to
from
to

1991- to-1996
1.50
1.38
1.62
2.08
1.90
2.27

1997-to-2001
1.65
1.53
1.77
2.01
1.85
2.18

2002-to-2006
1.71
1.60
1.83
2.18
2.03
2.34

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':(Z, W)}, where (X, Y) and (Z, W) 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':(3, 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)}.