Table 1 Demographic characteristics of the study sample (N = 49,507)

Sample size

5442

7546

7686

7571

7465

7363

6434

Male (%)

2638 (48)

3801 (50)

3703 (48)

3660 (48)

3581 (48)

3542 (48)

3056 (47)

Female (%)

2804 (52)

3745 (50)

3983 (52)

3911 (52)

3884 (52)

3821 (52)

3378 (53)

Age (years)

38.62 (30.00,46.54)

40.20 (30.56,48.82)

42.44 (33.05,50.85)

45.14 (35.83,53.25)

46.26 (37.47,54.37)

46.94 (38.86,55.61)

48.62 (40.77,56.86)

< 0.001

Smoke

< 0.001

No (%)

3528 (65)

4978 (66)

5180 (67)

5052 (67)

5061 (68)

4997 (68)

4423 (69)

Yes (%)

1914 (35)

2565 (34)

2502 (33)

2516 (33)

2403 (32)

2366 (32)

2011 (31)

Drink

< 0.001

3406 (63)

4647 (62)

4883 (64)

4943 (65)

4907 (66)

4722 (64)

4170 (65)

2036 (37)

2889 (38)

2788 (36)

2626 (35)

2557 (34)

2641 (36)

2264 (35)

Energy intake (1000 kcal/d)

2.373 (1.959,2.836)

2.428 (2.019,2.929)

2.326 (1.913,2.797)

2.258 (1.841,2.747)

2.290 (1.845,2.821)

2.163 (1.779,2.622)

2.053 (1.637,2.557)

< 0.001

Total physical activity(100METs/d)

2.11 (1.00,3.37)

2.60 (1.28,4.56)

2.07 (1.03,4.00)

1.73 (0.80,3.46)

1.72 (0.76,3.33)

1.75 (0.84,3.28)

1.85 (0.90,3.25)

< 0.001

Education level

< 0.001

2902 (53)

3692 (49)

3321 (43)

2974 (39)

2778 (37)

2678 (36)

2279 (35)

1651 (30)

2369 (31)

2575 (34)

2665 (35)

2592 (35)

2754 (37)

2422 (38)

888 (16)

1472 (20)

1782 (23)

1930 (25)

2093 (28)

1931 (26)

1733 (27)

Marital status

< 0.001

625 (11.5)

965 (12.8)

809 (10.5)

582 (7.7)

466 (6.2)

375 (5.1)

267 (4.1)

4682 (86.0)

6318 (83.7)

6578 (85.6)

6655 (87.9)

6668 (89.3)

6581 (89.4)

5779 (89.8)

21 (0.4)

46 (0.6)

68 (0.9)

92 (1.2)

93 (1.2)

128 (1.7)

138 (2.1)

114 (2.1)

217 (2.9)

231 (3.0)

242 (3.2)

238 (3.2)

279 (3.8)

250 (3.9)

Individual income (Yuan)

2595.48 (1502.49,4392.02)

3564.56 (2055.24,5714.71)

4432.20 (2355.11,7263.67)

5261.33 (2693.60,9672.23)

6024.26 (2872.05,10,962.58)

8889.46 (4832.47,15,685.91)

11,036.93 (5860.76,18,708.16)

< 0.001

Urbanicity index

43.94 (32.75,60.88)

51.21 (35.18,66.90)

55.19 (42.69,76.76)

58.74 (44.27,81.11)

61.85 (47.26,82.31)

64.09 (51.07,84.69)

67.99 (51.63,86.24)

< 0.001

WC (cm)

74.0 (70.0,80.0)

77.0 (71.0,83.2)

78.0 (72.0,85.0)

80.0 (74.0,87.0)

80.0 (74.0,87.5)

82.0 (75.0,89.2)

83.0 (76.0,90.4)

< 0.001

Height (cm)

160.0 (154.1166.0)

160.4 (154.9166.8)

160.8 (155.0,167.2)

161.0 (155.3167.5)

161.2 (156.0,168.0)

161.5 (156.0,168.0)

161.7 (156.0,168.0)

< 0.001

HC (cm)

89.0 (85.0,94.0)

91.0 (86.6,96.0)

93.0 (88.0,98.0)

93.0 (88.0,98.0)

93.1 (89.0,98.2)

94.1 (89.5,99.8)

95.0 (90.0,100.0)

< 0.001