Table 1.
General characteristics of participants aged 18–60 years.
| General Characteristics | Survey Year 1 | |||||||
|---|---|---|---|---|---|---|---|---|
| 1991 | 1993 | 1997 | 2000 | 2004 | 2006 | 2009 | 2011 | |
| n | 4926 | 5212 | 5441 | 6036 | 5318 | 5112 | 5134 | 4560 |
| Age (year) 2 | 36.2 ± 0.2 2 | 36.4 ± 0.2 | 37.8 ± 0.2 | 39.1 ± 0.1 | 41.7 ± 0.2 | 42.6 ± 0.2 | 42.7 ± 0.2 | 43.7 ± 0.2 |
| 18–39 (%) | 61.4 | 59.7 | 53.9 | 50.4 | 41.7 | 38.3 | 37.6 | 32.6 |
| 40–60 (%) | 38.6 | 40.3 | 46.1 | 49.6 | 58.3 | 61.7 | 62.4 | 67.4 |
| Male (%) | 47.7 | 48.5 | 50.6 | 50.0 | 48.9 | 48.5 | 48.5 | 47.5 |
| Income (CNY) 3 | ||||||||
| Low | 4.0 ± 0.1 | 4.1 ± 0.1 | 5.1 ± 0.1 | 5.3 ± 0.1 | 6.0 ± 0.1 | 6.4 ± 0.1 | 10.3 ± 0.1 | 12.1 ± 0.2 |
| Medium | 9.6 ± 0.1 | 10.3 ± 0.1 | 12.8 ± 0.1 | 15.1 ± 0.1 | 16.8 ± 0.1 | 18.9 ± 0.1 | 28.2 ± 0.1 | 34.4 ± 0.2 |
| High | 22.1 ± 0.3 | 25.9 ± 0.3 | 30.8 ± 0.4 | 38.4 ± 0.6 | 46.5 ± 0.6 | 57.5 ± 1.2 | 78.8 ± 1.3 | 92.5 ± 1.6 |
| Urbanicity (score) 2 | ||||||||
| Low | 25.5 ± 0.1 | 26.6 ± 0.1 | 28.8 ± 0.1 | 35.2 ± 0.1 | 36.9 ± 0.1 | 38.4 ± 0.1 | 42.4 ± 0.1 | 44.4 ± 0.1 |
| Medium | 36.9 ± 0.1 | 39.7 ± 0.1 | 42.1 ± 0.1 | 47.3 ± 0.1 | 49.3 ± 0.1 | 51.9 ± 0.1 | 55.3 ± 0.1 | 58.1 ± 0.1 |
| High | 52.8 ± 0.2 | 55.9 ± 0.2 | 61.5 ± 0.2 | 67.5 ± 0.2 | 73.0 ± 0.3 | 75.6 ± 0.2 | 77.8 ± 0.3 | 80.1 ± 0.2 |
1 Significant trend in the subgroup of age, income, and urbanicity across the survey years (p < 0.01; test for trend). Percentage of males did not significantly change over time (p-trend > 0.05). 2 Mean ± SE (all such values). 3 Adjusted to Chinese yuan value in 2011 (per 1000 yuan).