The dependences of solar disk-area coverages by sunspots (blue) and faculae (red) on solar age. Plotted are the dependences calculated with the S-index averaged over the activity cycle (solid lines) as well as the dependences obtained using the S-index at the minimum and maximum of the activity cycle (dashed lines below and above corresponding solid lines, respectively). The diamond symbols represent the disk-area coverages by sunspots (blue) and faculae (red) calculated with annual S-index values obtained from the Sac Peak CaII measurements of solar cycle 23. The rotational period indicated along the top horizontal axis is calculated assuming that it is proportional to the square root of age (Skumanich 1972).