I always got this split from Elite packs.
Probably depends on your luck a bit with a long-term average of 1/2,5/3,5. Not taking the chance of two rares in a pack into account.
NEWS ALERT: Ultimate Pack has just been updated to 12 chars (Min 3 Rares) for 90 Creds.
DUN DUN DUUUUN!
I wonder what the average split it has...
I'm guessing 3/4/5 or 3/3/6. Also, the new packs look awesome.