Upper panel: annual (b + y)/2 values versus time according to the spectral solar irradiance (SSI) reconstructions to the past as calculated by Krivova et al. (2010) (red), Lean et al. (2005) (blue) and Shapiro et al. (2011) (magenta: thick and thin curves are original data and data with removed secular changes, respectively). Stars indicates the SIM/SORCE measurements. Lower panel: calculated for the 20 year time intervals rms₂₀ values versus time.