Evolution of magnetic field amplitude over redshift for different models of effective Reynolds number. The curves and shaded areas correspond, respectively, to the average and the 90% confidence interval given by the averaging process described in Appendix C. The age of the Universe t_U at each redshift is plotted on the second x-axis. Each row corresponds to a different model, and each column corresponds to a different starting redshift of the dynamo. Model L (top row) has the lowest growth rate, while Models M and U (middle and bottom rows, respectively) show faster growth rates. The figure also shows that the dynamo was much faster in the past (higher redshift values).