What gives?

I often wonder how many times a year I get sick. 4? 6? 8? I guess it depends on what you define sick as, for me, it's having to take forced days off the bike, or a day in bed, or something similar. Whatever the definition, it can't be denied that I seem to get sick. A. LOT.

I eat well generally, I eat well on the bike 90% of the time, I eat well after rides 100% of the time, I generally take recovery pretty seriously (when I can), I try and avoid germy people, I am super careful about scheduling split sessions, if I feel something coming on I cut out strength and back it off on the bike if need be.

Yet I still get sick.

What gives, immune system?