WASHINGTON (CNN) -- More U.S. soldiers committed suicide in 2007 than at any time since the first Gulf War, according to an Army study to be released Thursday.
There were at least 115 suicides last year, or 18.8 for every 100,000 soldiers serving in the Army, said an Army official with access to the report.
The military still is investigating another two possible suicides.
The new figure is up from 102 in 2006.
More than two in five of the suicides came after soldiers returned home from deployments, the study shows.
The military is set to announce the findings officially later Thursday. CNN obtained some statistics from the study before publication. Watch why the Army blames stress on personal relationships »
Roughly one in four of the soldiers who killed themselves were on their first deployments, according to the study. About the same percentage killed themselves without ever having been deployed. Forty-three percent committed suicide after coming home.
The statistics cover active-duty Army troops, including National Guard and reserve soldiers. The numbers do not account for other branches of service.
There are about 1.08 million troops serving in the Army, according to the Defense Department, comprising 525,000 on active duty, 194,000 in the Army Reserve and the Army National Guard's 356,000.
The Army recorded 87 suicides in 2005, 67 in 2004 and 79 in 2003, the year the Iraq war began. The war in Afghanistan began in October 2001.
It is difficult to compare the military suicide rate with that of the private sector because of demographic differences and overall human stress factors, officials have said.
According to a Pentagon report released last summer, the overall suicide rate for the United States was 13.4 per 100,000 people in 2006.
For all men ages 17 to 45, it was 21.1 per 100,000 people, compared with 17.8 for men in the Army.
And it was 5.46 per 100,000 for all women, compared with an Army rate of 11.3 women soldiers per 100,000.
The Army concluded in the 2007 report that the "main indicators" for the 2006 suicides were failed relationships, legal and financial problems and "occupational/operational" issues.
The "typical profile" of a soldier who commits suicide is a member of an infantry unit who kills himself with a firearm.
CNN's Barbara Starr and Jamie McIntyre contributed to this report.