How about classes? Well, the stereotype is true: more Blood Elves are Paladins than are any other class (35%). This has made Paladins 6th most popular class for the Horde, which is kind of surprising for a class that just became available recently. Who thought so many Hordies had been secretly longing to bubble-hearth? This having been said, Draenei Shaman are even more popular, relatively speaking, than Blood Elf Paladins -- 49% of Draenei are Shaman. That's a lot of space totems. This also means Draenei represent almost half (48%) of all the Shaman in the game; 39% of Paladins are Blood Elves. Due to the relative unpopularity of Draenei, though, Shaman is still the least popular Alliance class, as it has been for the game's history (not entirely by choice for most of it, of course).
All of this data is from the ever-lovely WarcraftRealms.com census data, and ignores characters below level ten. Head over there if you want more detailed stats of any kind. How is your realm doing?