Those charts prove to me that there is a fairly large percentage of the pilot group who fear the retributions of calling in sick over holidays. They would rather come to work sick rather than visit the CP office and deal with explaining why they called in sick over a holiday.
We've all heard it before, "If you call in sick over a holiday it is a guaranteed trip to see the CP."
If we would get a policy that did not allow the company to call us in or ask for verification for ANY sick calls during the first 100 hours of sick usage and move the renewal date to our anniversary month instead of May, I'll bet the sick usage would even out to about the average.