EU:
Garrison: 1,017,490
Silver: 84,369,644
NA:
Garrison: 482,179
Silver: 27,312,480
NA fiefs : 109 (smaller map, fiefs not being there)
EU fiefs : 180
So when you do the maths, NA stacking =
-25% than EU stacking (not much)
Still, despite the map being smaller (for playerbase reason officially?) there is a lot of players NA side for that few fiefs. To reach a measly 500k in garrison for almost as many strategus players as EU, NA must have fough about 2.5x more than EU.
I think NA deserve 180 fiefs even more than EU does. Even though one could argue that the scarcity of fiefs is an incentive for more battles.