Age

Number

Detection Rate/%

χ²

P-Value

6 (N = 10)

0

0.00

5.42

0.491

7 (N = 125)

6

4.80

8 (N = 110)

9

8.18

9 (N = 166)

15

9.03

10 (N = 163)

14

8.59

11 (N = 155)

18

11.61

12 (N = 46)

3

6.52