Ms.Miller, while this is in IL. and not Indianna.I would say is typical for the western states,The following appeared in the St.Charles Chronicle May 23,1929 in a article called "Americanism".
"St. Charles Township with a population of 1882, sent 453 such sons to the Civil War, a per capita record unequaled by any other community in the North it is claimed with some authenticity."
Roughly 1/4 of the population.Take numbers mustered times .25 that would give you a rough estimate of Indianna Population at the time of the war.

Below are generalities
Total # Inf.Regtx1500 including Rec.
" "# Cav.Regt.x2000
" "# Art.Regt.x500
" "# Engineer Regt.x1500

Illinois sent 256,297 men to the war effort
I hope this helps!