People (n) at entry and years of follow up in different age groups
| Age at entry | People (n) | Cohort follow up (y) (median, 25th–75th percentiles) |
| 15–29 | 8451 | 20, 15–22 |
| 30–34 | 3448 | 21, 19–23 |
| 35–39 | 3142 | 21, 19–23 |
| 40–44 | 3122 | 21, 19–23 |
| 45–49 | 3652 | 21, 20–23 |
| 50–54 | 4134 | 21, 19–22 |
| 55–59 | 4041 | 21, 18–22 |
| 60–64 | 3063 | 21, 18–22 |
| 65–69 | 442 | 21, 18–23 |
| 70–74 | 8 | 21, 16.5–22.75 |
| Total | 33503 | 21, 18–22 |