How many non-combatants were killed in the Holocaust?

The NAZI's were very efficient in killing the innocent Jews. By definition, the Jews who were the victims of the Holocaust were all non-combatant German, Austrian, Polish etc. citizens. None of the others killed in the war were categorized as Holocause victims. The NAZI's were also very efficient in destroying their records. We may never have an exact number of Holocaust victims. We can only estimate, based on the size of the graves, the number of skeletons found, the number of German/Polish/Austrian, Jewish citizens before the war compared to the number found after the war.