Summary: Remember the Set.2 booster box with only 2 URs? Yes. Jirva was one of the best Set.2 card, but still spending close to $100 and get only 2 URs was nothing but a disappointment. In fact, I bet some people stop buying boxes because of this. So does Set.3 have these disappointing boxes?
Japan was the same. Japanese booster box consists of 12 booster packs rather than 36 packs i.e. 3 Japanese booster box = 1 US booster box. In Set.2 there were Japanese Booster boxes that did not have ANY UR.
There has been active post on Japanese forum regarding to what URs people has pulled. So far it sounds like people are getting on average 2 URs/box. With occasional 1 UR/box or 3 UR/box. No report of 0 UR box yet. Assuming this applies to other regions as well, US or UK booster box likely contain 5-7 URs per box just like with the Set.1.
Well done Upper deck!