John Goekler nicely summarizes the stats:
The single greatest killer of Americans is the so-called "lifestyle disease." Somewhere between half a million and a million of us get a short ride in a long hearse every year because of smoking, lousy diets, parking our bodies in front of the TV instead of operating them, and downing yet another six pack and / or tequila popper.

According to the US Department of Health and Human Services, between 310,000 and 580,000 of us will commit suicide by cigarette this year. Another 260,000 to 470,000 will go in the ground due to poor diet and sedentary lifestyle. And some 85,000 of us will drink to our own departure.

After the person in the mirror, the next most dangerous individual we're ever likely to encounter is one in a white coat. Something like 200,000 of us will experience "cessation of life" due to medical errors -- botched procedures, mis-prescribed drugs and "nosocomial infections." (The really nasty ones you get from treatment in a hospital or healthcare service unit.)

The next most dangerous encounter the average American is likely to have is with a co-worker with an infection. Or a doorknob, stair railing or restaurant utensil touched by someone with the crud. "Microbial Agents" (read bugs like flu and pneumonia) will send 75,000 of us to meet the Reaper this year.

If we live through those social encounters, the next greatest danger is "Toxic Agents" -- asbestos in our ceiling, lead in our pipes, the stuff we spray on our lawns or pour down our clogged drains. Annual body count from these handy consumer products is around 55,000.

After that, the most dangerous person in our lives is the one behind the wheel. About 42,000 of us will cash our chips in our rides this year. More than half will do so because we didn't wear a seat belt. (Lest it wrinkle our suit.)

Some 31,000 of us will commit suicide by intention this year. (As opposed to not fastening our seat belts or smoking, by which we didn't really mean to kill ourselves.)

About 30,000 of us will die due to our sexual behaviors, through which we'll contract AIDS or Hepatitis C. Another 20,000 of us will pop off due to illicit drug use.

The next scariest person in our lives is someone we know who's having a really bad day. Over 16,000 Americans will be murdered this year, most often by a relative or friend.
Thanks to Schneier.