Well, it is a percentage, so the Law of Large Numbers means someone will get hit by it eventually, given a large enough sample size. I'd suggest it went "way up" if there were a bunch of people noticing it, in which case it would likely be a bug.
Otherwise, it's just always been there... there aren't many ferries on which to be captured, so the sample size is smaller.
Oh, and if I wasn't clear, by land points I mean one landlocked region to another, not a sea route.