Table 1 Demographic characteristics of the sample and SMS prevalence

Age (years)

0.15

0.9977

<25

3010

15.0

26.4

25-34

4394

20.7

25.9

35-44

3883

19.7

25.5

45-54

2755

19.5

27.3

55+

2824

25.0

26.2

Ethnicity

0.26

0.6098

Han

15203

91.9

26.5

Other

1663

8.1

22.7

Gender

6.83

0.0089

Male

8795

46.9

32.8

Female

8071

53.1

20.4

Education

12.97

0.0047

Elementary school or less

1899

10.7

48.4

Junior high school

5213

27.0

29.8

High school

4914

31.0

19.1.

Junior college or more

4840

11.3

22.6

Occupation

26.07

0.0002

Managers and clerks

1553

7.5

61.7

Professionals

1291

6.2

40.5

Commerce and service

2914

15.7

26.9

Operations

2344

23.8

22.4

Students

1541

8.1

29.5

Retired

2286

21.1

17.4

Other

4932

28.6

20.7

Income/person/year Yuan*

111.87

<0.0001

<10,000

3818

21.6

43.4

10,000-19,999

5090

27.2

33.3

20,000-29,999

3677

21.2

18.8

30,000-39,999

1754

12.2

10.8

40,000-49,999

1157

8.2

11.4

50,000+

1370

9.8

16.4

Region variance

Region location

0.73

0.6939

East

6469

49.8

23.1

Central

2566

10.6

26.2

West

7831

39.6

30.3

GDP

16.25

0.0003

<40,000

7713

39.0

36.1

40,000-59,999

3944

26.1

30.4

60,000+

5209

34.8

12.1

Population(million)

7.20

0.0275

<5

7026

22.0

23.6

5-

5960

30.8

28.4

10 -

3880

46.9

16.6