^Sheet is a little old but still "close"^
Maybe Shamans are just to popular atm for the changes we have been asking for. In a perfectly even world each of the 11 classes would make up about 9% of any given statistical population whereas shamans are around 11.5% of the PvE population(6/14H+) and 12.5% in PvP(1800+).
Even though shamans seem to be successful enough to be popular in late game activities they are unfortunately not very balanced "within" the class. In the loosely defined(6/14H+) "high end" PvE bracket about 54% of the shamans are Ele and in 1800+ PvP about 55% of shamans are resto. But I think you will find shamans are not at all alone in this...
I made a couple of little spreadsheets in an effort to show off the PvE numbers.
It might help you to think of it like "23 of every 100 tanks are prot paladins".
I wish I had found 10vs25 statistics since I assume the Blizz Devs are expecting larger average raid sizes to have an impact on these types of numbers in PvE. I am looking forward to keeping track of these stats when all "high end" raiding is 20man as the numbers will be truer then with only one standard.
Well I had a bunch of fun looking at this stuff and playing with numbers I hope some of you guys enjoy it as well :]