This study is not measuring the number of DUI per car model. It's measuring the amount of drivers that have had a DUI in their life, per car model. So this stu

This study is not measuring the number of DUI per car model. It's measuring the amount of drivers that have had a DUI in their life, per car model. So this study could start by normalising against the age of drivers, because the older the drivers, the more likely they've have had a DUI strike in their life.