There are all kinds of figures thrown about but i doubt if any one actually knows. But i can say it contributed to my Wifes death with lung cancer, and the Heart attack i had which i ended up with 5 bypasses the doctors said my smoking was the only cause they could say with some certainty as my cholestral was well below the danger spot. Then i had a bout of bladder cancer which doctors say is linked to smoking. And how do you explain the healthy as horses people in there 80's and 90's who smoke heavily and never seem to run out of energy.