Distributions of the IMF orientation solar wind-magnetosphere coupling function factor, sin⁴(θ/2), for 1996–2016 (inclusive) for various averaging timescales, τ, where θ = tan⁻¹(|B_Y|/B_Z) where B_Y and B_Z are the Y- and Z-components of the IMF in the Geocentric Solar Magnetospheric (GSM) reference frame: (a) τ = 5 min; (b) τ = 1 h; (c) τ = 6 h; (d) τ = 1 day; (e) τ = 27 days; (f) τ = 1 yr. N is the number of samples in each sin⁴(θ/2) bin, the largest value of which for a given τ is N_max. In each panel the red dashed line is the overall mean for the whole dataset which, because the averaging intervals of length τ contain equal numbers of samples, equals the mean of each distribution (the “mean of means” or the “grand mean”). The raw B_Y and B_Z data used are of resolution 5 min and have been rounded up/down to 2 decimal figures.