On my 3rd round still only ONE prod bonus
(with 4,5% chance) while I got on my very first round (1,5% chance) at least 3 or even 4 times such bonus !
I would suggest the like some others already did, to make it more visual when you get a bonus
AND also this :
I suggest to give the % chance an extra boost WHEN, I as "Thane of the Vikings", bring Diplomacy high enough during the building up of the Vikings Settlement !
So it's even more important to have a plan and LOGICAL it is that the Vikings work harder and better (giving bonus!) when I raise "diplomacy" continious high enough
Just only "an example" : when producing Axes have at least 55 diplomacy to get a chance for a bonus ... while prod Mead at least 90 D, while prod Horns 240 D, while prod Wool 545 D, something like that for getting an even better chance for a prod. bonus.
Just a "suggestion", do not know if such is possible to work out, but see it as a nice challenge !