Hi guys,
If it helps, I made a census of the population of Elysium.
http://imgur.com/4iCXEY5
http://imgur.com/wTQxWeP
The blue rectangles represent the number of players per level. I pruned the database by removing characters not seen in 30 days.
In total 8416 Horde, 7260 Alliance.
Level 60 : 302 Horde, 396 Alliance. Then into the end-game the difference is almost irrelevant for the moment.
The increased distribution of Horde players is manifested between level 20 and level 40. I think that the difference of 1,000 players is "physiological" for the moment.
Sorry for my english. Have fun!