1920's (no official post-season until 1932) : 1 1st place finish at the Chicago Staleys (not Decatur...)
1930's: 4 playoff appearances, 2 championships, 2 championship losses
1940's: 5 playoff appearances, 4 championships (the one in 1940 was the all time ass kicking of Wash 73-0), 1 championship loss
The reality is the Pap Bears kicked ass until the 70's.
Then the 80's we kicked ass again.
Then the 00's we did OK and lost a SB.
Other than before the 70's and during the 80's...it's been sparce.