Star-formation rate as a function of redshift for all galaxies used. Red dashed lines correspond to the boundaries between the 3 different bins used to make comparative stacks, which are labeled (1), (2), and (3). As an inset on the left, we show the stacked spectrum (signal-to-noise of Hα weighted average) of all the galaxies in the sample. The lines of Hα, [Nii]λλ6548,6583, and [Sii]λλ6716,6731 are all significantly detected, but we can only set an upper limit on the [Oi]λ6300 emission.