| Baseline | 6 month | 6 month change | 12 month | 12 month change | 18 month | 18 month change | 24 month | 24 month change | |
| All participants | 7.7 | 6.9 | -0.8 | 6.6 | -1.1 | 6.9 | -0.8 | 6.4 | -1.3 |
| Males | 7.5 | 6.9 | -0.6 | 6.0 | -1.5 | 6.2 | -1.3 | 6.3 | -1.2 |
| Females | 8.0 | 6.9 | -1.0 | 7.1 | -0.9 | 7.3 | -0.7 | 6.4 | -1.5 |