6 m | n | 9 m | n | 12 m | n | 18 m | n | 24 m | n | |
---|---|---|---|---|---|---|---|---|---|---|
All participants | 83.4 | 67 | 85.5 | 63 | 86.8 | 65 | 87.8 | 61 | 89.6 | 55 |
(SD) | (18.9) | (18.6) | (17.3) | (18.6) | (18.9) | |||||
Income > $20,000 | 85.8 | 61 | 87.6 | 57 | 88.8 | 60 | 89.7 | 56 | 92.3 | 50 |
(SD) | (17.0) | (17.9) | (15.7) | (17.1) | (16.9) | |||||
Income ≤ $20,000 | 59.8 | 6 | 64.7 | 6 | 62.2 | 5 | 66.0 | 5 | 62.4 | 5 |
(SD) | (22.7) | (12.5) | (19.6) | (22.9) | (17.4) |