This references several previous answers of mine here and here. I give an overview of how the draft functioned in the United States during the World War II years here.
Roughly 10 million of the 16 million personnel (slightly less than two-thirds) that served in the United States armed forces between 1940 and 1946 were conscripted; 9,920,436 between November 1940 and December 31, 1945, and 10,110,104 between November 1940 and October 1946, if the period between January 1, 1946 and when the Director of Selective Service suspended all inductions on October 16 is considered.
Separating the number of casualties and casualty rate suffered by drafted versus voluntarily enlisted personnel is an exceedingly laborious task that would require extensive primary source research, something not necessarily impossible, but which feels outside the bounds of this question. We could just assume that about two-thirds of casualties were incurred by those personnel who were drafted.
The common pop history (and even academic history) assertion that "replacement troops died faster" has very rarely been substantiated with factual data, although it is possible to do such a thing; Robert S. Rush's PhD thesis "Passchendaele With Tree Bursts" about a two-week period in the Hürtgen Forest proves exactly the opposite in the case of one regiment.
The U.S. Army reached its peak size during the spring of 1945 at 8.3 million personnel, of which 2.75 million were serving in the Army Ground Forces and 1.75 million the Army Air Forces. 234,874 Army men paid the ultimate price in battle during World War II.
Front-line infantry duty was exceedingly dangerous during World War II, and those serving faced relatively low odds of returning unscathed, either mentally or physically. After prolonged combat, the "revolving door" effect began to set in. Of 757,712 Army Infantry branch personnel that deployed overseas, 661,059 battle casualties were incurred, a rate of 87.2% of the total strength;
| Deployed overseas | Total battle casualties | Deaths among battle casualties | KIA | DOW | Died while MIA | Died while POW | WIA | MIA | POW |
|---|---|---|---|---|---|---|---|---|---|
| 757,712 | 661,059 | 142,962 | 117,641 | 19,613 | 1,795 | 3,913 | 471,376 | 15,830 | 56,212 |
The 35th Infantry Division was a National Guard unit originally made up of troops from the states of Nebraska, Kansas, and Missouri. In combat from July 1944 until May 1945, the unit took part in well-known battles such as the Normandy breakout, Patton's push through the Lorraine, and the Battle of the Bulge. Despite the alarming casualty figures, the 35th Infantry Division was only "middle of the road" in this regard;
| Total battle casualties | Deaths among battle casualties | KIA | DOW | Died while MIA | Died while POW | WIA | MIA | POW |
|---|---|---|---|---|---|---|---|---|
| 15,822 | 2,997 | 2,485 | 462 | 24 | 26 | 15,822 | 340 | 1,471 |
Company L of the 3rd Battalion, 134th Infantry Regiment, had its armory (or rather, not-armory, as there are several articles in the Omaha World-Herald during the war detailing the effort to renovate the old city auditorium for such a purpose) in Omaha, Nebraska. In May 1944, immediately before departure for England from Camp Kilmer, New Jersey, 149 of the 193 men (77.2%) in the company were draftees and a large portion were not from Nebraska at all, owing to the large turnover in units stateside between 1940 and 1944;
Men of Company L by Origin, May 1944:
| Number | Description |
|---|---|
| 87 | Draftees not from the Seventh Service Command |
| 62 | Draftees from the Seventh Service Command (Colorado, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, South Dakota, Wyoming) |
| 29 | Federalized National Guard soldiers from Nebraska |
| 3 | Volunteers from the Seventh Service Command |
| 3 | Volunteers not from the Seventh Service Command |
| 3 | Federalized National Guard officers from Nebraska |
| 3 | Federalized National Guard officers not from Nebraska |
| 1 | Federalized National Guard soldier not from Nebraska |
| 1 | Pre-war Regular Army volunteer |
The "revolving door" effect in action. The unit received 663 replacements during its combat service, either obtained from replacement units or other divisions, or from other companies within the 134th Infantry Regiment;
| Month | KIA | DOW | SWA | SIA | LWA | LIA | MIA | POW | Sick | NBC | Total |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 7/44 | 37 | 3 | 16 | 111 | 5 | 1 | 6 | 6 | 10 | 195 | |
| 8/44 | 9 | 1 | 7 | 36 | 6 | 3 | 15 | 3 | 80 | ||
| 9/44 | 15 | 2 | 1 | 30 | 3 | 13 | 2 | 1 | 67 | ||
| 10/44 | 3 | 3 | 3 | 2 | 11 | ||||||
| 11/44 | 24 | 12 | 124 | 8 | 1 | 20 | 43 | 232 | |||
| 12/44 | 8 | 13 | 46 | 7 | 22 | 89 | 14 | 3 | 202 | ||
| 1/45 | 6 | 3 | 2 | 16 | 21 | 14 | 62 | ||||
| 2/45 | 2 | 2 | 6 | 3 | 10 | 1 | 24 | ||||
| 3/45 | 1 | 28 | 1 | 6 | 36 | ||||||
| 4/45 | 4 | 1 | 9 | 14 | |||||||
| 5/45 | 2 | 2 | |||||||||
| Total | 105 | 4 | 55 | 3 | 404 | 52 | 30 | 108 | 101 | 63 | 925 |