James, studies on ranking drug harms allow for prevalence. Harmfulness is not just one value but a consideration of a range of factors eg risk of mortality, short-term long term damage to person, risk of dependence, risk to society (criminogenicity, road smashes..). With illicit drugs , many of these factors are aggravated by prohibitionist policies. Alcohol tends to beat most other drugs for harm when you sum all the factors, People mistakenly tend to take its legality as a signal of its safety when compared with "real drugs". Hence we can have a Prime Minister, often seen with a glass or bottle in his hand, claiming he doesn't agree with drugs, as if that is a useful policy statement.