Table 1 Percentage (and n) of boys and girls reporting daily consumption

11 y boys

42.4% (331)

30.7% (287)

4.4% (34)

9.2% (71)

83.2% (664)

81.7% (627)

11 y girls

56.5% (449)

40.0% (316)

5.7% (45)

5.7% (45)

80.7% (636)

86.7% (680)

Gender diff ^χ2

p < .001

p < .001

ns

p < .01

ns

p < .01

13 y boys

34.7 (287)

27.4% (226)

9.2% (76)

14.1% (117)

76.2% (632)

87.4% (726)

13 y girls

44.7% (337)

30.5% (229)

9.6% (72)

11.0% (83)

65.9% (494)

82.9% (622)

Gender diff^χ2

p < .001

ns

ns

p < .05

p < .001

p < .01

15 y boys

31.6% (257)

22.6% (184)

12.9% (105)

21.0% (171)

66.4% (539)

84.7% (689)

15 y girls

40.7% (291)

29.7% (212)

13.1% (94)

13.7% (98)

51.6% (368)

77.6% (553)

Gender diff^χ2

p < .001

p < .01

ns

p < .001

p < .001

p < .001

16 y boys

21.4% (186)

17.5% (152)

11.1% (97)

22.5% (196)

60.1% (525)

84.7% (689)

16 y girls

38.5% (228)

29.2% (249)

15.4% (131)

14.0% (119)

55.3% (471)

78.8% (670)

Gender diff^χ2

p < .001

p < .001

p < .01

p < .001

ns

p < .01

Grade diff ^χ2

p < .001

p < .001

p < .001

p < .001

p < .001

ns