Panel a): annual mean numbers of sunspot groups. The black line with gray shading depicts the result of this work with the 68% confidence interval. Numerical values are given in Table A.1. Other colored curves with symbols show reconstructions of G by H98 (Hoyt & Schatten 1998), S16 (Svalgaard & Schatten 2016), and U16 (Usoskin et al. 2016b). Panel b): ratio between the colored plots (shown in panel “a)” and following the same notation) to the result of this work. The ratio is not shown for years with low activity (G < 3).