Comparison between RGO010 and RGO000 group counts, represented as the differences between the raw data ($\mathrm{\Delta }G=G_A^{\mathit{RC}}-G_A^{\prime }$; panel a), and those calibrated with the method listed in each panel ($\mathrm{\Delta }G=G_A^{\prime \mathit{RC}}-G_A^{\prime }$), for different temporal coverage. The overlaps are colour-coded as denoted at the top of the figure, while the full overlap is in black. Shown are the annual mean values. To visualise the phase of the solar cycle, we also show, as a shaded grey surface, a scaled version of the group counts from RGO. The numbers at the bottom of each panel denote the conventional solar cycle numbering.