Histograms of Δϖ/σ[Δϖ] (top panel), Δμ_α*/σ[Δμ_α*] (middle panel) and Δμ_δ/σ[Δμ_δ] (bottom panel) for 2882 source-lens pairs (black histograms). In the top panel, the red curve is a Gaussian with zero mean and standard deviation of unity, scaled to match the histogram of Δϖ/σ[Δϖ]. In each panel, the blue histogram with striped bars is for the source-lens pairs satisfying Δϖ/σ[Δϖ] > 3.