(a) Power-law exponent calculated from the total SN (black), and from its portion belonging to the following cycle over the overlap period (the exponent fit in red and the linear transition in blue, see text for details). Only the solid lines were used for the calculation, and the transition between models is at solar minimum (dotted vertical line). (b) and (c) Exponential fit of the power-law exponent of cycles 21 and 22 in the overlap period with cycles 20 and 21, respectively. The “×” symbols are the estimated exponents from Table 3, based on the observations by Harvey (1993) and our analysis of the RGO/SOON record. The error-bars mark the uncertainty ranges in x (time) and y (exponent) directions, see text and Table 3 for details. The horizontal line is the power-law exponent m = −3.94 which corresponds to a SN of zero.