Easy. Germans (being Germans) kept meticulous records (at it was actually in the neighborhood of 5.8M to include many other "untermenschen"). Years ago whilst in college I saw the official German records captured (the National Archives have a bunch) and no doubt in my mind they waxed that many.
Nuh uh. Those records were faked by the bolsheviks who infiltrated and cooked the books to make the Nazis look like baddies.
