While this link lists killed & wounded, I'm hoping to find a study which analyzes what percentage of each MOS receives disability ratings or disability retirements or regular pensions or Reserve/Guard pensions. A study has to start with data like this, and I'm hoping that an agency or think tank has turned it into information.
I don't think you'll find large scale data on MOS/AFSC and disability available to the public (edit: guess I was wrong and should have kept reading as there is a study linked above for the army). It wouldn't surprise me if the RAND Corp has completed a study on retirement by AFSC.
Here is my small sample observations relating to the Air Force. The most common conditions I saw rated for disability were conditions correlated with an increase in age. Luckily the obviously combat related, highly political and highly visible cases are relatively rare and they don't impact the overall statistics like people think they would based on the visibility. The common conditions are seen across all MOS/AFSC's roughly equally, therefore the number of people who receive a disability in each MOS/AFSC is proportional to the number of people in each MOS/AFSC. There may be some statistically significant abnormalities where MOS/AFSC X has a high rate of condition Y but I didn't see it in the numbers, despite the fact that there are clearly jobs that are more physically demanding than others and I feel like there should be.
The VA releases aggregated information on their claims and it seems to sync with my small sample size opinions pretty well. The most prevalent service connected disabilities in 2013 were:
Tinnitus - 1,121,709 7.0%
Hearing loss - 854,855 5.3%
Post-traumatic stress disorder - 648,992 4.0%
Lumbosacral or cervical strain - 616,937 3.8%
Scars, general - 574,191 3.6%
Limitation of flexion, knee - 453,704 2.8%
Diabetes mellitus - 398,480 2.5%
Paralysis of the sciatic nerve - 346,572 2.2%
Limitation of motion of the ankle - 343,834 2.1%
Degenerative Arthritis of the Spine - 335,692 2.1%
I don't think this really tells the full story as there are literally hundreds of specific conditions (if not thousands) and a better representation is cases by body system (with the common name for the most common conditions in that category):
Musculoskeletal 541,280 (Lower back pain)
Auditory 222,139 (Ringing of the ears/hearing loss)
Skin 150,423 (Scars)
Neurological 133,195 (Damaged/pinched nerve specifically the Sciatic nerve which ranges in severity of symptoms)
Mental 100,515 (PTSD)
Respiratory 70,058 (Sleep Apnea)
Digestive 53,258 (Hernias)
Cardiovascular 41,494 (High blood pressure)
Genitourinary 50,291 (Erectile Dysfunction)
Endocrine 26,056 (Diabetes)
The Eye 15,385 (Conjunctivitis)
Dental /Oral 7,139 (Limited jaw movement)
Gynecological 6,340 (Hysterectomies)
Hemic/Lymphatic 3,626 (Anemia)
Infection /Immune/Nutrition 2,129 (Malaria)
On the subject of PTSD there seems to be a lot of talk about RPA pilots and PTSD and studies have shown their rate of PTSD to be equivalent to manned pilots. It's also rare, with a less than 1% occurrence rate. I think a lot of the concern is media generated and by movies like "Good Kill" that recently came out. The incidence among pilots is less than the incidence among those in health care, administrative/supply, combat-specific, and the AF overall. I figure many people will find the fact that there is a higher incidence of PTSD in administrative/supply than pilots interesting but I believe that's due to a general lack of understand about what PTSD is and what can contribute to the condition, just like there is a general lack of understanding about most mental/behavioral health conditions.
References for people who want more or have differing statistics/opinions:
http://www.benefits.va.gov/REPORTS/abr/ABR-Compensation-FY13-09262014.pdfhttp://www.benefits.va.gov/warms/bookc.asp#phttps://timemilitary.files.wordpress.com/2013/04/pages-from-pages-from-msmr_mar_2013_external_causes_of_tbi.pdf