Yes, and this is true of many other wars.
In the Revolutionary War, about 8,000 died in combat, 17,000 to other causes, probably disease and exposure.
In the War of 1812, 2,260 died in combat but 12,740 died to other causes.
Mexican-American War, 1,733 in combat, 11,550 to other causes.
Civil War actually had a higher proportion of soldiers killed in battle - probably due to the nature of the fighting: huge numbers of men standing in front of each other and shooting and a huge amount of men fighting in a rather small space. ~ 215,000 died in combat, ~ 450,000 died to other causes, again, likely disease and exposure.
We got "better" at killing people moving forward, World War I had 53,402 combat deaths to 63,114 to other causes.
WWII - 291,557 to combat and 113,842 to other causes. From what I've read, because medicine and sanitation was much better by WWII, the number of men killed by disease was drastically reduced and that the vast majority of those killed died as a result of accident: ship sinks, truck rolls over, airplane crashes in fog, etc.
By Korea, 33,686 to combat and only 2,830 to other causes.
Vietnam 47,424 combat deaths, 10,785 to other causes.
big difference in Korea and Vietnam in the ratio of accidental death to combat death.
Afghanistan 1,833 combat deaths to 383 other causes.
Iraq 3836 combat deaths to 961 other causes.
Purely my speculation here but I'd say that the higher ratio of accidents in Iraq is due to driving. Troops drive a lot in Iraq but fly more in Afghanistan and driving is about one of the most unsafe things to do, especially in heavy military vehicles.
And completely off topic, it was safer to be stationed as a US service member in Iraq in 2006, at the height of the war, than to be stationed in the US or Germany in 1973. The reason: traffic accidents. More soldiers died in America and Germany, driving their own cars, by ratio, than died in Iraq during the war. So it was safer to be in war in 2006 than home in 1973.