Table 2 Change in risk factor prevalence: percent of the dead exposed to each of five risk factors.* Estimates for 1982 and 2001 are from a line fitted to the data for all years.†.

Risk factor	Prevalence in 1982 (%)	Prevalence in 2001 (%)	Difference (%)	95% CI for difference (%)
Alcohol	56	36	−20	−20 to −19
No seat belt	94	55	−39	−40 to −39
No air bag	100	53	−48	−48 to −47
No motorcycle helmet	60	44	−16	−18 to −15
No bicycle helmet‡	100	94	−4	−6 to −3

*Only some dead people were considered to be at risk for some factors: for example, only vehicle occupants (not motorcyclists) were considered at risk for not wearing a seat belt and only motorcycle riders were considered at risk for not wearing a motorcycle helmet.

†Change difference  =  final year prevalence minus first year prevalence. Change estimate restricted to 1992–2001 for air bags and 1994–2001 for bicycle helmets.

‡Failure to wear a bicycle helmet assumed to be 100% before 1994.