Table 1

Distribution of person years (%) covered by the study by age and parental social class

AgeParental social class
Upper non-manualLower non-manualManualFarmerEntrepreneurOtherAllPerson years (1000s)
5–92024386751002874
10–142026387821002904
15–191925407721002829
20–241522459621003025
25–2912184515731003329
30–3410164418751001888