Table 1. Participant characteristics using the Complex Samples Procedure (N = 1,214).

Characteristic variables	N (%)
Age (in years)	45.3±16.7
≤30	300(24.7)
31~45	344(28.8)
46~60	306(25.2)
≥61	264(21.7)
Gender
Male	432(35.6)
Female	782(64.4)
Level of Education
Primary school or below	246(20.3)
Junior high school	359(29.6)
Senior high school /Technical secondary school	286(23.6)
Junior college	197(16.2)
Bachelor’s degree or above	126(10.4)
Household monthly income (CNY * )
<2,000	81(6.7)
2,000~3,999	587(48.4)
4,000~5,999	368(30.3)
6,000~7,999	123(10.1)
≥8,000	55(4.5)

*.CNY Chinese yuan; 6.21 CNY = 1 USD