Time

Number of cases

Healthy

Sick

Qualification

Months

196

156 (79.6%)

40 (20.4%)

7. 47 ± 2.24

1 year

132

110 (83.3%)

22 (16.7%)

7. 84 ± 2.34

2 to 5 years

382

325 (85.1%)

57 (14.9%)

8.08 ± 2.09

6 to 9 years

156

147 (94.2%)

9 (5.8%)

8.54 ± 1.82

10 years or more

186

175 (94.1%)

11 (5.9%)

8.67 ± 1.69