Easy/Hard pass mark

Does anyone buy into the theory that the difficulty of exam cycles between hard and easy?

I think the grading committee mostly has a forced hand when setting the pass rate. I'm sure they look at a distribution of scores, and since the scores are discrete, there are many candidates with scores around the pass mark. If they move the pass mark by one point, it could cause the passing % to jump by 5%. All this to say, I know the committee is shooting for a particular range (probably 45-55% passing), but I think they do have some flexibility in choosing where in the range the pass mark falls.

So maybe there's something to this theory that there is a cycle between "easy" and "hard" meaning the way the committee sets the pass mark. What do you think? The recent data seems to suggest so. Here is the past data starting with Spring 2015:

GHADV 52.7 46.8 53.2 46.2
GHCORU 44.3 50.2 46.2 48.8
GHSPC 71.9 52.7 60.4
ERM 45.6 44.3 43.4 44.3


Easy/Hard pass mark