find . -name '*.[ch234]' | xargs fold -b1 | sort | uniq -c | awk '{total += $1; values[$2] = $1} END {for (v in values) { print v, values[v], values[v] / total} }' | sort

$ 959 0.000463706
0 28148 0.0136104
1 15078 0.00729068
% 1214 0.000587006
- 13282 0.00642225
! 1333 0.000644546
. 19889 0.00961694
| 1996 0.000965127
2 11967 0.00578641
~ 212 0.000102509
/ 22146 0.0107083
; 23911 0.0115617
] 2528 0.00122237
[ 2541 0.00122865
, 27208 0.0131559
) 31425 0.015195
( 31598 0.0152786
& 3284 0.00158791
^ 329 0.000159082
\ 3375 0.00163192
` 352 0.000170203
_ 36064 0.0174381
* 36090 0.0174506
3 8604 0.0041603
< 3914 0.00189254
@ 411 0.000198731
 415231 0.200777
: 4262 0.00206081
= 44072 0.0213102
' 4461 0.00215703
4 7127 0.00344612
+ 5587 0.00270149
5 6200 0.00299789
} 6392 0.00309073
{ 6397 0.00309315
6 5893 0.00284945
# 7293 0.00352639
7 5521 0.00266957
> 8166 0.00394851
8 5453 0.00263669
? 873 0.000422122
" 9370 0.00453068
9 5060 0.00244667
A 15296 0.00739609
a 61040 0.0295147
b 15723 0.00760255
B 6333 0.0030622
c 38092 0.0184187
C 9133 0.00441609
d 38123 0.0184336
D 9264 0.00447943
e 105655 0.0510874
E 19497 0.0094274
f 37434 0.0181005
F 7552 0.00365162
g 16782 0.00811461
G 4995 0.00241524
h 24858 0.0120196
H 4193 0.00202744
I 18100 0.00875191
i 75964 0.0367309
J 159 7.68814e-05
j 1864 0.000901301
K 1390 0.000672108
k 6509 0.0031473
L 17574 0.00849757
l 46995 0.0227235
m 20755 0.0100357
M 5111 0.00247133
N 14489 0.00700588
n 69597 0.0336523
O 13466 0.00651122
o 56386 0.0272644
p 26075 0.0126081
P 6737 0.00325755
q 1614 0.000780419
Q 391 0.000189061
R 13679 0.00661422
r 61908 0.0299344
S 16592 0.00802274
s 58055 0.0280714
T 17086 0.00826161
t 88773 0.0429245
u 38510 0.0186208
U 8378 0.00405102
v 12447 0.00601851
V 2605 0.0012596
W 2376 0.00114887
w 7306 0.00353268
x 18791 0.00908603
X 2171 0.00104975
y 11287 0.00545761
Y 2650 0.00128136
Z 387 0.000187126
z 4783 0.00231273