Table 1 Baseline characteristics of study sample

Age (year), mean ± SD

40.11 ± 13.35

40.09 ± 13.48

  Before 1920

0.30

0.22

  1920–1929

2.62

1.94

  1930–1939

6.43

6.56

  1940–1949

9.52

11.68

  1950–1959

15.23

16.28

  1960–1969

25.58

22.65

  1970–1979

28.50

27.73

  1980–1989

10.85

11.87

  After 1990

0.97

1.07

  Some elementary school

1.02

5.89

  Elementary school

9.09

14.22

  Junior high school

6.30

6.62

  Senior high school

20.38

22.26

  College

20.32

18.40

  University

28.09

25.65

  Graduate school or higher

14.80

6.97

Height (cm), mean ± SD

169.96 ± 6.49

157.50 ± 5.88

Weight (kg), mean ± SD

69.56 ± 11.39

54.96 ± 9.08

Body mass index (kg/m²), mean ± SD

24.05 ± 3.47

22.19 ± 3.66