Table 3
Perforations in each age category
Age (y)
Group A
Group B
Total
0–4
—
9/11 (82%)
9/11 (82%)
4–8
5/12 (42%)
15/21 (71%)
20/33 (61%)
>8
7/39 (18%)
31/46 (67%)
38/85 (45%)
Total
12/51 (24%)
55/78 (71%)
67/129 (52%)