Sorry, I should have put the sources list at the bottom of my reply.
First off you can't compare US mortality rates to Irish ones, especially if you can't apply it to the numbers.
From the Wikipedia article on Tuam: Writing in a 2012 HSE report, Declan McKeown, a consultant public health physician and medical epidemiologist stated that the infant mortality rate in the home were "similar to those recorded at Bessborough" (another mother and baby home), which were five times the rate for Ireland in 1950 and 65 times the 2012 rate. McKeown stated that these rates were equivalent to the infant mortality rate in Ireland in the 1700s.
That seems disturbingly high, don't you think?
EDIT: Disturbingly high and a common occurence in these facilities in Ireland.
Also check out at least that 1st Arte video. It is not long and features a couple of survivors.
After consuming the sources below I have to say that the disposal of the bodies is IMHO the least atrocious thing that was committed.
Sources:
Here is some more links on the disturbing stuff: