Daily Rate number of Deaths Person- Mortality rate difference cigarettes from lung years per 1000 Rate per 1000 smoked cancer at risk person-years Ratio person-years O 3 42,800 0.07 referent referent 1-14 23 38,600 15-24 56 38,900 25+ 62 25,100 1 1 1 1 All smokers 141 102,600 Total 144 145,400