Data from "Grade Distribution in 80 Midwestern Liberal Arts Colleges"
by Frank G. Edson,
School and Society, 73:312-315 (1951).
Number of colleges awarding each interval of percent of letter grades.
	A	B	C	D	F
1 to 5%	3  (3.8%)			10  (13%)	72  (92.5%)
6 to 10%	8  (10%)			45  (57%)	6  (7.5%)
11 to 15%	36  (45.6%)			18  (23%)
16 to 20%	20  (25.2%)		1  (1.3%)	4  (5%)
21 to 25%	8  (10%)	3  (3.8%)	3  (3.8%)	1  (1.3%)
26 to 30%	2  (2.5%)	16  (20%)	8  (10%)
31 to 35%	1  (1.3%)	34  (43%)	25  (32%)
36 to 40%	1  (1.3%)	19  (24%)	18  (23%)
41 to 45%		6  (7.6%)	16  (20%)
46 to 50%		1  (1.3%)	8  (10%)
total	79	79	79	78	78
Average of grade distributions of 74 institutions
	raw data	adjusted
A	15.2	16.0
B	31.1	32.7
C	36.4	38.3
D	9.1	9.6
F	3.2	3.4
total	95	100