40% and 61%
The percentages of "tobacco use prevalence, including both smokeless and smoking" in, respectively, the Air Force and the Marine Corps (the lowest and highest percentages among the service branches), according to an article in the June 2016 issue of Military Medicine -- Installation Tobacco Control Programs in the U.S. Military. "Tobacco use rates also vary significantly by rank," according to the article. "For example, cigarette smoking prevalence is 30% for the lowest ranking personnel but only 3.7% for the highest." The researchers determined that "the military as an institution is not fully engaged in tobacco control effort." For one thing, they note, "Evaluation of cessation programs is lacking, so there is no clear direction for improvement."
The article concludes:
A Defense Advisory Committee on Tobacco has prepared recommendations for DoD-wide tobacco control policy; they have not yet been released. Policy change represents the best option for ending the tobacco epidemic. In this regard, the military has some advantages and some disadvantages compared to civilian institutions. Because it is both responsible for and dependent on the good health of its members, and because it has the authority, it could implement stringent rules about tobacco use (such as prohibiting tobacco use in uniform, during duty hours, or altogether). Such rules are beyond the scope of most civilian organizations. However, there are restrictions on the policy options available. For instance, recent Congressional action requires military exchanges to continue to sell tobacco products. There is a history of Congress stepping in at the behest of the tobacco industry when military tobacco control proponents attempt to establish strong policies, so there may be reluctance to act aggressively.