Evolution of the total unsigned photospheric magnetic flux over time. Red: Our reconstructions based on the ISNv2 (top) and CEA17 GSN (bottom). Blue: Reconstruction of Krivova et al. (2021) (based on ISNv2 in the top panel, HoSc98 GSN in the bottom panel). Symbols: Total magnetic flux measurements from WSO, MWO, and NSO/KP; black line: their average. All quantities are shown as one-CR averages. The contribution of the SSE is scaled by a factor of 0.4 to compensate for the limited spatial resolution of observations.