Composites of fractional disc coverage by plage as a function of time (upper panel) using the data from Ko (blue) and MW (green) as the reference. Also shown is the average of the two composites (red), and the unscaled plage areas from Rome/PSPT (black). The shaded surfaces give the asymmetric 1σ interval, while the solid lines are annual median values. Lower panel: ratio (black) and difference (blue) between the annual values of the composites based on the Ko and MW series. The dotted horizontal line denotes the ratio of 0.5 and difference of 0 in disc fractions. The numbers under the curves in both panels denote the conventional SC numbering.