[currymesurprise]

That is the expected result for a sub-population that has a shorter lifespan.

My sibling comment addresses deaths lagging over time. But even in the steady state of (say) 18% smokers, you expect more than 18% of deaths to be smokers because their life expectancy is shorter.

[jimrandomh]

If every time a smoker dies you blame it on smoking, then sure. But while smoking is really terrible, it's not quite that terrible; smokers still manage to die of unrelated things sometimes.