Cumulative rate of G1 to G4 storm days during the first 4 years of solar cycles 17–24; the symbol indicates the cycle number. Error bars are given by the square root of the number of storm days. The storm rates during cycle 24 (blue squares) are clearly below those in the previous cycles, in particular for the weaker storms where there are better statistics. Note also that the rates for cycles 17, 20, and 23, the weaker cycles in Figure 1 tend to lie below those for the stronger cycles.