Beijing | Guangzhou | |||
Age group | Mean ± SD | n | Mean ± SD | n |
20s | 24.79 ± 2.29 | 90 | 26.14 ± 2.00 | 74 |
30s | 35.52 ± 2.72 | 27 | 35.06 ± 3.16 | 49 |
40s | 44.13 ± 3.09 | 62 | 44.45 ± 2.97 | 56 |
50s | 55.20 ± 3.63 | 45 | 54.59 ± 4.01 | 37 |