Although the numbers are debated and very rough, I used the statistics from Wikipedia and found the number of military dead as a percentage of population for each of the two world wars. I then averaged those percentages to come up with a combined "misery index" by country:
Germany 5.5%Everyone who had terrible casualties in WW I (arbitrarily defined as greater than 1.2% casualties) had much lower casualty rates in WWII except for one country: Germany. Germany went from 3.1% to 7.9%.
United Kingdom 1.4%
Being able to accept those sort of casualties is just unbelieveable, especially just 20 years after the end of the first. How militaristic Germany must have been, and how willing the citizens to die!
Most countries who suffered extreme casualities during the first war did not in the second; France (surely in recoil from WWI casualties) basically bowed out of WWII. The opposite also happened in some cases, such as with Russia where the death rate when from around 1% to 6%. But in Germany there was the high death rate in both. (For Serbia, I lumped WWII's Yugoslavia in with them. For Austria-Hungary, WWII I lumped in only Hungary.)