Post-Traumatic Stress Disorder

I believe the number is higher. Many soldiers do not want to admit they are suffering from PTS.

Nearly one in 10 American soldiers who served in Iraq were diagnosed with post-traumatic stress disorder, most after witnessing death or participating in combat, a study said on Tuesday.
Mental health screening of veterans showed 21,620 out of 222,620 returning from Iraq and assessed over the year ending April 30, 2004, suffered from post-traumatic stress -- a disorder that can lead to nightmares, flashbacks and delusional thinking.

Overall, 19.1 percent of soldiers and Marines who returned from Iraq met the military's "risk criteria for a mental health concern" such as post-traumatic stress or depression, compared to 11.3 percent among veterans who served in Afghanistan and 8.5 percent from deployments elsewhere, the report published in the Journal of the American Medical Association said.

Here is an article on Marine Christian Lopez dealing with PTS.

The good news is more soldiers and Marines are seeking help than the Vietnam era. Treatment is the first step. Veterans can contact the Readjustment Counseling Service.