I'd defer to the DND-CAF ombudsman's report on that one. They did the more intense research on it. Their finding was that there is not reliable data on it. I'm not intending to speak for the ombudsman's office by any stretch, but they identified as an absolute need the requirement to make sure there's compliance with tracking of illnesses and injuries, as per proper reservist practice. I think that goes on within the reserves more broadly, and can be a problem within the CAF, as some serving personnel are reticent to be recorded as having gotten an injury or illness for fear that it may somehow be used against them when they're going out.
Given the informal nature of clearing people for heading out on the land as rangers, I think some of those concerns on the part of rangers will also have to be considered in ensuring that rangers feel comfortable sharing that information and tracking it.