Not that anybody asked, but here's the order of frequency for chars in the .pm files (lib/5.../*.pm and */*.pm) in 5.00503 and 5.6.1:

 etsia
nrold$hucmfp)(b    ;=y_g,'.:>"-E
w{}CTIvS#kANOxRL<PM/D@F\1UqB0HG[]2V*&|+zXWY%j~!?^3K549786ZJQ`ö 

 etisanr
oldhucmf$pb()yg=_;-,#.    >':"
wCE}{TvISkAxN<OR\PL/MF0D@1qUBH2[]G*|&VzX+%Wj?3~^Y5!4K6987ZJQ`
[download]

I inserted the linefeeds before the w's so's to fit.  The tabs are between b and ; and between . and > , in case they don't travel.
The only mildly surprising thing is that the uppercase is used more than the numerals. (and j is used very little, and there's more )'s than ('s in 5.005, hmmm)

Of course, the perl fingerprint is the buck($) being in the first 20 characters while all the digits are past the 60th.

  p