EKA-FKN is a wide range. That's a good 50% or so of the printed polymer 100s. While they're getting slightly less frequent due to age and newer releases, I wouldn't consider it any rarer than getting a 5 that starts with HB.
I still see plenty of $5s with prefixes starting with HB in Newfoundland, though I do admit, I seem to see slightly fewer now. The odds of finding a prefix like HBJ, to name one, are very slim in my province nowadays.
Though I do admit, I did come across a M/C HBG $5 recently, in the 1.3 million range. Unfortunately, I spent it afterwards.