borderline significantp=0.08
Annual increases by age group Annual increases differed by age group as indicated by the borderline significant interaction between study year and age group (p=0.08), and showed smaller increases in the younger age group (age 2–5 year: 2.4%, 95% CI 1.9% to 2.9%) compared with the older age groups (5.1% and 5.7%, respectively, in 6–10 year olds and 11–15 year olds).