(Grey histograms) Average pdfs for all years of (a) 〈Ap〉_τ=1day/〈Ap〉_τ=1yr and (b) 〈Pα〉_τ=1day/〈Pα〉_τ=1yr . In each case the best-fit lognormal distribution is shown, with mean of unity (by definition) and a variance v = 0.934 in (a) and v =0.913 in (b). Distributions for individual years (not shown) are a bit noisier, particularly for 〈Pα〉_τ=1day/〈Pα〉_τ=1yr in years when data availability f is low, but give very similar best fit v values, as indicated by the horizontal uniformity of the bottom panels of figures (6) and (7): for the annual normalised Ap distributions, the mean ± 1 standard deviation of the fitted v values for the 53 years is 0.934 ± 0.031; for the annual normalised Pα distributions, v values for the 31 years with f > 0.5 is 0.915 ± 0.025.