Results of the reconstruction of E(z) (=H(z)/H₀) using the SN1a and BAO data, normalized by the values for our fiducial cosmology given by the best-fitting parameters from the Planck analysis for a ΛCDM model. Each thin line comes from a random draw among the points in parameter space within 68% confidence level. The thick line in the middle represents the best fit. The uncertainties are relatively large at z = 1 − 1.5 since the error bars of the Baryon acoustic oscillations (BAO) measurements at z = 0.8, and especially, at z = 1.5, are significantly larger, while SN1a measurements are only powerful enough to constrain the splines at z ∼ 0.8 − 1. The shape of expansion history is described by piecewise natural cubic splines. The splines constrained by the data can be used to constrain D_s/D_ds and hence break the internal MST.