It is generally accepted that of the total German military combat deaths in WWII, which numbered about 3.4 million, about 75% and possibly 80% were on the eastern front. Additionally, up to June 1944 (Normandy) the percentage was even higher since there was little combat elsewhere that generated large casualties.
German material losses on the eastern front were also huge representing over 80% of artillery, tank and truck losses. Aircraft losses were about 50/50 on the eastern and western front. Of course, naval losses were almost exclusively in the west, even including defensive actions taken against Soviet attempts to massacre civilians on the open seas late in the war in the Baltic.
It is said that, 9 out of 10 German soldiers killed in World War II were on the Eastern Front.