Illustration of long-term drop in CDS\NIS responsivity. The CCD readout bias has been removed from the data right after reading them in. No other calibration has been applied to the data. The solid lines and their associated error bars represent the mean and the standard deviation of the average intensity values over 90-day time intervals. The vertical dashed-lines indicate the two one-year time spans which we used to compare the two solar activity minima.