Year Employees
1933 593.433
1934 630.905
1935 656.223
1939 659.943
1937 703.546
1938 778.374
1939 958.000
1940 1.145.600
1941 1.253.100
1942 1.386.000
1943 1.529.000
1944 1.581.000

Sources used

Alfred C. Mierzejewski - The Most Valuable Asset of the Reich: A History of the German National Railway 1933-1945