Scatter plots for limb-CME speed over the period 1998–2014 versus the microwave fluences: (a) ϕ_3 GHz, (b) ϕ_9 GHz and (c) ϕ_max. The solid coloured lines represent the linear fits obtained by different methods: least absolute deviation (green), least squares (orange) and total least squares (blue). Red arrows show upper limits of the fluences, blue arrows the lower limits of ϕ_max.