Anecdotally, a number of FI course instructors tell me that the numbers are way down, which is no surprise.
There was a peak before JAR FCL came in with many people getting in before the entry requirements became more difficult. Also, in practice you now need to get your CPL(H) before FI rating so people may be concentrating on that before (possibly) doing the FI course.
My guess is that the numbers will be permanently down, but JAR FCL has also reduced the number of people starting PPL(H)s, so there is less work for instructors too.