Maybe they should have put not all rare cities in column three. Then everything would be less obvious. I have two cities in column 3, to conquer Italy, I still need Naples. My only country conquered so far is Sweden.
So my guess is that Sweden and Italy are the most easiest countries to conquer. Not only are there big differences between column 1, 2 and 4 countries on the one hand and column 3 countries on the other hand. There are also big differences in column 3 with Sweden being much more likely than Australia, Canada or Germany. I wouldn't be too surprised to find the rarest city only 10 times in the whole deck.
But this promo is great fun anyway, just love reading regs on the internet who blame party that they don't have 200 % rakeback for this promo and conquer all countries within 8 days.