Only 2% of the Union army were draftees. Over 20% of the Confederate army were draftees.
Firstly, you are making a tue quoque argument. Secondly, I think your numbers are either false, or falsely reported. My reading of History recalls the circumstance of Irish immigrants being grabbed newly arrived off the ships in American Harbors. No doubt these were listed as "volunteers."
I do not begrudge a nation's right to draft it's citizens to fight in that nation's wars, but to draft immigrants from other nations, to help them fight in a war in which they had no stake? That is just dirty.