"The DoDSER annual report, which covers up to the end of 2011, is full of useful information. It shows that those who commit suicide are more likely to be white, in their mid-20s, divorced, with a rank of private and a basic high-school education." [US military suicides in charts: how they overtook combat deaths].
The Guardian UK's post has a number of charts that add a little more detail to the above quote. One chart shows that while there has been a sharp decrease in deaths in military action, there has been a rather sharp increase in suicides. In fact for the first time there are more suicides than military deaths - 349 to 311.
Another chart indicates that those military personnel with a GED had the highest rate per 100,000 military population - 42.51. High school graduate rate is 18.79 and officers at 12.54. It is an inverse correlation - I wonder why? A quick Google search shows no causal relationship in the general population, see e.g., The relationship between general p... [Suicide Life Threat Behav. 2009] - PubMed - NCBI.
I was mostly surprised at the data. Check it out.