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Figure 1.

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(a) The Wolf (WSN) and Hoyt & Schatten (1998a, 1998b) Group (GSN) sunspot number time series, for their 1700–1995 period of overlap. Cycle numbers are given at the bottom of the plot. (b) The two groupings of new sunspot number time series: (1) SN* (Clette & Lefèvre 2016) and RGS (Svalgaard & Schatten 2016); and (2) RWL (Lockwood et al. 2014a, 2014b, 2016b), RGU (Usoskin et al. 2016a), and RWF (Friedli, personal communication, 2016). Cycle numbers are given at the bottom of the plot.

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