100 = time since seen is ignored (pure random), 0 = a just-seen
comic almost never reappears (its weight is floored at one millisecond
of time-since-seen, ~4·10⁻¹⁰ of a never-seen comic); in between, a
comic's chance grows linearly with time since you saw it
d
h
min
comics seen longer ago count as unseen again (all zero = never forget)
Comics by Randall Munroe