Filament butterfly diagrams constructed from the observations of all Hα archives. The diagrams show daily mean areas within latitudinal strips of 1° as fractions of the area of the entire solar disc. White means no observed filaments, and blue denotes the filament fractional areas that become darker with growing areas up to the saturation level of 2×10⁻⁴. A vertical black line marks the separation of archives when more than one archive is included in a panel, except for MD, where it marks the instrument upgrade over 2017.