| Age group (years) | classification | ||||
| Not significant Freq (%) | Mild Freq (%) | Advanced Freq (%) | Severe Freq (%) | Total Freq (%) | |
| 18 - 27 | 13 (2.6) | 14 (2.8) | 2 (0.4) | 2 (0.4) | 31 (6.2) |
| 28 - 37 | 90 (18.0) | 70 (14.0) | 5 (1.0) | 18 (3.6) | 183 (36.6) |
| 38 - 47 | 83 (16.6) | 66 (13.2) | 4 (0.4) | 14 (2.8) | 167 (33.4) |
| 48 - 57 | 40 (8.0) | 41 (8.2) | 12 (2.4) | 5 (1.0) | 98 (19.6) |
| 58 - 67 | 10 (2.0) | 8 (1.6) | 1 (0.2) | 2 (0.4) | 21 (4.2) |
| Total | 236 (47.2) | 199 (39.8) | 24 (4.8) | 41 (8.2) | 500 (100.0) |