Amplitude of the rotational solar brightness variability (black curves) and its facular (red) and spot (blue) components calculated for the 1999–2014 period (panel a)), as well as averaged over the years 2000 (panel b)) and 2008 (panel c)). The green shaded contours indicate the transmission curves of the Strömgren filters b and y. The dark (light) shaded areas show Kepler (CoRoT) total spectral efficiency.