Table 1 Characteristics of Study Population in 2002 and 2018.^a

No

2668

4419

Age, year

46.5 ± 16.1

48.7 ± 16.8

 < 0.001

Male, %

47.7%

49.3%

0.193

Urban area, %

53.6%

52.4%

0.332

Han ethnicity, %

98.0%

94.8%

 < 0.001

Education attainment, %

 Primary school or lower

27.5%

22.1%

 < 0.001

 Junior high school

58.0%

54.5%

 < 0.001

 Senior high school or above

14.5%

23.4%

 < 0.001

 Body mass index, kg/m²

25.0 ± 5.0

25.9 ± 3.9

 < 0.001