instantaneous
If b(t) is the number of busy units, and c(t) is the current capacity, then the instantaneous utilization iu(t) is
if b(t) = 0, then iu(t) = 0.0 if b(t) greater than or equal to c(t) then iu(t) = 1.0 else iu(t) = b(t)/c(t)